diff --git a/src/main/java/me/topchetoeu/jscript/common/Instruction.java b/src/main/java/me/topchetoeu/jscript/common/Instruction.java
index f4884ae..60251f9 100644
--- a/src/main/java/me/topchetoeu/jscript/common/Instruction.java
+++ b/src/main/java/me/topchetoeu/jscript/common/Instruction.java
@@ -17,11 +17,13 @@ public class Instruction {
         TRY_END(0x06),
 
         CALL(0x10),
+        @Deprecated
         CALL_MEMBER(0x11),
         CALL_NEW(0x12),
-        JMP_IF(0x13),
-        JMP_IFN(0x14),
-        JMP(0x15),
+        CALL_SUPER(0x13),
+        JMP_IF(0x18),
+        JMP_IFN(0x19),
+        JMP(0x1A),
 
         PUSH_UNDEFINED(0x20),
         PUSH_NULL(0x21),
@@ -59,6 +61,7 @@ public class Instruction {
         KEYS(0x52),
         TYPEOF(0x53),
         OPERATION(0x54),
+        EXTEND(0x55),
 
         GLOB_GET(0x60),
         GLOB_SET(0x61),
@@ -282,15 +285,17 @@ public class Instruction {
         return new Instruction(Type.NOP, params);
     }
 
-    public static Instruction call(int argn, String name) {
-        return new Instruction(Type.CALL, argn, name);
+    public static Instruction call(int argn, boolean hasSelf, String name) {
+        return new Instruction(Type.CALL, argn, hasSelf, name);
     }
-    public static Instruction call(int argn) {
-        return call(argn, "");
+    public static Instruction call(int argn, boolean hasSelf) {
+        return call(argn, hasSelf, "");
     }
+    @Deprecated
     public static Instruction callMember(int argn, String name) {
         return new Instruction(Type.CALL_MEMBER, argn, name);
     }
+    @Deprecated
     public static Instruction callMember(int argn) {
         return new Instruction(Type.CALL_MEMBER, argn, "");
     }
@@ -300,6 +305,9 @@ public class Instruction {
     public static Instruction callNew(int argn) {
         return new Instruction(Type.CALL_NEW, argn, "");
     }
+    public static Instruction callSuper(int argn) {
+        return new Instruction(Type.CALL_SUPER, argn);
+    }
 
     public static Instruction jmp(int offset) {
         return new Instruction(Type.JMP, offset);
@@ -321,7 +329,6 @@ public class Instruction {
         return i -> new Instruction(Type.JMP_IFN, pos.getAsInt() - i);
     }
 
-
     public static Instruction pushUndefined() {
         return new Instruction(Type.PUSH_UNDEFINED);
     }
@@ -386,16 +393,18 @@ public class Instruction {
     public static Instruction loadRegex(String pattern, String flags) {
         return new Instruction(Type.LOAD_REGEX, pattern, flags);
     }
-    public static Instruction loadFunc(int id, boolean callable, boolean constructible, boolean captureThis, String name, int[] captures) {
+    // TODO: make this capturing a concern of the compiler
+    public static Instruction loadFunc(int id, boolean callable, boolean constructible, boolean captureThis, boolean noThis, String name, int[] captures) {
         if (name == null) name = "";
 
-        var args = new Object[5 + captures.length];
+        var args = new Object[6 + captures.length];
         args[0] = id;
         args[1] = name;
         args[2] = callable;
         args[3] = constructible;
         args[4] = captureThis;
-        for (var i = 0; i < captures.length; i++) args[i + 5] = captures[i];
+        args[5] = noThis;
+        for (var i = 0; i < captures.length; i++) args[i + 6] = captures[i];
         return new Instruction(Type.LOAD_FUNC, args);
     }
     public static Instruction loadObj() {
@@ -460,6 +469,9 @@ public class Instruction {
     public static Instruction defField(boolean enumerable) {
         return new Instruction(Type.DEF_FIELD, enumerable);
     }
+    public static Instruction extend() {
+        return new Instruction(Type.EXTEND);
+    }
 
     public static Instruction operation(Operation op) {
         return new Instruction(Type.OPERATION, op);
diff --git a/src/main/java/me/topchetoeu/jscript/common/environment/Environment.java b/src/main/java/me/topchetoeu/jscript/common/environment/Environment.java
index 0a33cec..02302d0 100644
--- a/src/main/java/me/topchetoeu/jscript/common/environment/Environment.java
+++ b/src/main/java/me/topchetoeu/jscript/common/environment/Environment.java
@@ -90,7 +90,7 @@ public class Environment {
         if (has(key)) return get(key);
         else return defaultVal;
     }
-    public <T> T get(Key<T> key, Supplier<T> defaultVal) {
+    public <T> T getWith(Key<T> key, Supplier<T> defaultVal) {
         if (has(key)) return get(key);
         else return defaultVal.get();
     }
diff --git a/src/main/java/me/topchetoeu/jscript/common/parsing/ParseRes.java b/src/main/java/me/topchetoeu/jscript/common/parsing/ParseRes.java
index 3bf2bb8..09b2c65 100644
--- a/src/main/java/me/topchetoeu/jscript/common/parsing/ParseRes.java
+++ b/src/main/java/me/topchetoeu/jscript/common/parsing/ParseRes.java
@@ -38,6 +38,11 @@ public class ParseRes<T> {
         return new ParseRes<>(state, errorLocation, error, null, 0);
     }
     @SuppressWarnings("unchecked")
+    public <T2> ParseRes<T2> chainError(ParseRes<?> other) {
+        if (!this.isError()) return other.chainError();
+        return (ParseRes<T2>) this;
+    }
+    @SuppressWarnings("unchecked")
     public <T2> ParseRes<T2> chainError(Location loc, String error) {
         if (!this.isError()) return new ParseRes<>(State.ERROR, loc, error, null, 0);
         return (ParseRes<T2>) this;
diff --git a/src/main/java/me/topchetoeu/jscript/compilation/ClassNode.java b/src/main/java/me/topchetoeu/jscript/compilation/ClassNode.java
index f265b00..af9585a 100644
--- a/src/main/java/me/topchetoeu/jscript/compilation/ClassNode.java
+++ b/src/main/java/me/topchetoeu/jscript/compilation/ClassNode.java
@@ -3,9 +3,13 @@ package me.topchetoeu.jscript.compilation;
 import java.util.ArrayList;
 import java.util.LinkedList;
 import java.util.List;
+import java.util.function.Consumer;
 
 import me.topchetoeu.jscript.common.Instruction;
+import me.topchetoeu.jscript.common.SyntaxException;
 import me.topchetoeu.jscript.common.Instruction.BreakpointType;
+import me.topchetoeu.jscript.common.environment.Environment;
+import me.topchetoeu.jscript.common.environment.Key;
 import me.topchetoeu.jscript.common.parsing.Location;
 import me.topchetoeu.jscript.common.parsing.ParseRes;
 import me.topchetoeu.jscript.common.parsing.Parsing;
@@ -14,6 +18,7 @@ import me.topchetoeu.jscript.compilation.members.FieldMemberNode;
 import me.topchetoeu.jscript.compilation.members.Member;
 import me.topchetoeu.jscript.compilation.members.MethodMemberNode;
 import me.topchetoeu.jscript.compilation.members.PropertyMemberNode;
+import me.topchetoeu.jscript.compilation.scope.FunctionScope;
 
 public abstract class ClassNode extends FunctionNode {
     public static final class ClassBody {
@@ -22,20 +27,29 @@ public abstract class ClassNode extends FunctionNode {
         public final List<Member> protoMembers;
         public final Parameters constructorParameters;
         public final CompoundNode constructorBody;
+        public final Node superExpr;
+        public final boolean hasConstr;
 
         public ClassBody(
             List<Member> staticMembers, List<FieldMemberNode> protoFields, List<Member> protoMembers,
-            Parameters constructorParameters, CompoundNode constructorBody
+            Parameters constructorParameters, CompoundNode constructorBody,
+            Node superExpr, boolean hasConstr
         ) {
             this.staticMembers = staticMembers;
             this.protoFields = protoFields;
             this.protoMembers = protoMembers;
             this.constructorParameters = constructorParameters;
             this.constructorBody = constructorBody;
+            this.superExpr = superExpr;
+            this.hasConstr = hasConstr;
         }
     }
 
-    // public static final Key<Void> 
+    public static final Key<Environment> CLASS_ROOT = Key.of();
+    public static final Key<Consumer<CompileResult>> SUPER = Key.of();
+    public static final Key<Consumer<CompileResult>> SUPER_PROTO = Key.of();
+    public static final Key<Consumer<CompileResult>> SUPER_CONSTR = Key.of();
+    public static final Key<Consumer<CompileResult>> ON_SUPER_CALL = Key.of();
 
     public final ClassBody body;
     public final String name;
@@ -43,7 +57,9 @@ public abstract class ClassNode extends FunctionNode {
     @Override public String name() { return name; }
 
     public void compileStatic(CompileResult target) {
-        for (var member : body.staticMembers) member.compile(target, true, false);
+        for (var member : body.staticMembers) {
+            member.compile(target, true, false);
+        }
     }
     public void compilePrototype(CompileResult target) {
         if (body.protoMembers.size() > 0) {
@@ -58,18 +74,71 @@ public abstract class ClassNode extends FunctionNode {
         }
     }
 
-    @Override protected void compilePreBody(CompileResult target) {
+    private void compileFieldInits(CompileResult target) {
         for (var member : body.protoFields) {
             target.add(Instruction.loadThis());
             member.compile(target, false, true);
         }
     }
 
+    @Override protected void compilePreBody(CompileResult target) {
+        if (target.env.hasNotNull(SUPER_PROTO)) {
+            if (!body.hasConstr) {
+                throw new SyntaxException(loc(), "Default constructors in derived classes not supported");
+                // compileFieldInits(target);
+            }
+        }
+        else compileFieldInits(target);
+    }
+
     @Override public void compile(CompileResult target, boolean pollute, String name, BreakpointType bp) {
-        var id = target.addChild(compileBody(target, name, null));
-        target.add(_i -> Instruction.loadFunc(id, false, true, false, name, captures(id, target)));
-        compileStatic(target);
-        compilePrototype(target);
+        if (body.superExpr == null) {
+            var id = target.addChild(compileBody(target, name, null));
+            target.add(_i -> Instruction.loadFunc(id, false, true, false, false, name, captures(id, target)));
+            compileStatic(target);
+            compilePrototype(target);
+        }
+        else {
+            var subtarget = target.rootEnvironment(JavaScript.COMPILE_ROOT).subtarget();
+            var protoVar = target.scope.defineTemp();
+            var constrVar = target.scope.defineTemp();
+
+            subtarget.env.add(SUPER_PROTO, t -> {
+                var i = t.scope.get(protoVar, false);
+                t.add(_i -> i.index().toGet());
+            });
+            subtarget.env.add(SUPER_CONSTR, t -> {
+                var i = t.scope.get(constrVar, false);
+                t.add(_i -> i.index().toGet());
+            });
+
+            var staticTarget = subtarget.subEnvironment();
+            staticTarget.env.add(SUPER, subtarget.env.get(SUPER_CONSTR));
+            staticTarget.env.add(CLASS_ROOT, staticTarget.env);
+
+            var protoTarget = subtarget.subEnvironment();
+            protoTarget.env.add(SUPER, subtarget.env.get(SUPER_PROTO));
+            protoTarget.env.add(CLASS_ROOT, protoTarget.env);
+
+            var constrEnv = subtarget.env.child();
+            constrEnv.add(SUPER, subtarget.env.get(SUPER_PROTO));
+            constrEnv.add(ON_SUPER_CALL, this::compileFieldInits);
+            constrEnv.add(CLASS_ROOT, constrEnv);
+
+            var id = target.addChild(compileBody(constrEnv, new FunctionScope(subtarget.scope), false, name, null));
+            target.add(_i -> Instruction.loadFunc(id, false, true, false, true, name, captures(id, target)));
+
+            body.superExpr.compile(target, true);
+
+            target.add(Instruction.extend());
+            target.add(Instruction.dup(1, 0));
+            target.add(Instruction.loadMember("prototype"));
+            target.add(_i -> protoVar.index().toInit());
+            target.add(_i -> constrVar.index().toInit());
+
+            compileStatic(staticTarget);
+            compilePrototype(protoTarget);
+        }
     }
 
     public ClassNode(Location loc, Location end, String name, ClassBody body) {
@@ -91,7 +160,18 @@ public abstract class ClassNode extends FunctionNode {
         var n = Parsing.skipEmpty(src, i);
         var loc = src.loc(i + n);
 
-        if (!src.is(i + n, "{")) return ParseRes.failed();
+        ParseRes<Node> superExpr = ParseRes.failed();
+
+        if (Parsing.isIdentifier(src, i + n, "extends")) {
+            n += 7;
+
+            superExpr = JavaScript.parseExpression(src, i + n, 14);
+            if (!superExpr.isSuccess()) return superExpr.chainError(src.loc(i + n), "Expected an expression after 'extends'");
+            n += superExpr.n;
+            n += Parsing.skipEmpty(src, i + n);
+        }
+
+        if (!src.is(i + n, "{")) return ParseRes.error(src.loc(i + n), "Expected a class body");
         n++;
         n += Parsing.skipEmpty(src, i + n);
 
@@ -105,7 +185,7 @@ public abstract class ClassNode extends FunctionNode {
 
         if (src.is(i + n, "}")) {
             n++;
-            return ParseRes.res(new ClassBody(statics, fields, members, params, body), n);
+            return ParseRes.res(new ClassBody(statics, fields, members, params, body, superExpr.result, false), n);
         }
 
         while (true) {
@@ -151,7 +231,7 @@ public abstract class ClassNode extends FunctionNode {
             else ParseRes.error(src.loc(i + n), "Expected a comma or a closing brace.");
         }
 
-        return ParseRes.res(new ClassBody(statics, fields, members, params, body), n);
+        return ParseRes.res(new ClassBody(statics, fields, members, params, body, superExpr.result, hasConstr), n);
     }
 
     // public FunctionStatementNode(Location loc, Location end, Parameters params, CompoundNode body, String name) {
diff --git a/src/main/java/me/topchetoeu/jscript/compilation/CompileResult.java b/src/main/java/me/topchetoeu/jscript/compilation/CompileResult.java
index 04711d5..c0fb4e1 100644
--- a/src/main/java/me/topchetoeu/jscript/compilation/CompileResult.java
+++ b/src/main/java/me/topchetoeu/jscript/compilation/CompileResult.java
@@ -10,6 +10,7 @@ import me.topchetoeu.jscript.common.FunctionBody;
 import me.topchetoeu.jscript.common.Instruction;
 import me.topchetoeu.jscript.common.Instruction.BreakpointType;
 import me.topchetoeu.jscript.common.environment.Environment;
+import me.topchetoeu.jscript.common.environment.Key;
 import me.topchetoeu.jscript.common.mapping.FunctionMap;
 import me.topchetoeu.jscript.common.mapping.FunctionMap.FunctionMapBuilder;
 import me.topchetoeu.jscript.common.parsing.Location;
@@ -142,7 +143,21 @@ public final class CompileResult {
     }
 
     public CompileResult subtarget() {
-        return new CompileResult(new Scope(scope), this);
+        return new CompileResult(env, new Scope(scope), this);
+    }
+
+    public CompileResult setEnvironment(Environment env) {
+        return new CompileResult(env, scope, this);
+    }
+    /**
+     * Returns a compile result with a child of the environment that relates to the given key.
+     * In essence, this is used to create a compile result which is back at the root environment of the compilation
+     */
+    public CompileResult rootEnvironment(Key<Environment> env) {
+        return new CompileResult(this.env.get(env).child(), scope, this);
+    }
+    public CompileResult subEnvironment() {
+        return new CompileResult(env.child(), scope, this);
     }
 
     public CompileResult(Environment env, Scope scope, int length, Consumer<CompileResult> task) {
@@ -154,11 +169,11 @@ public final class CompileResult {
         this.length = length;
         this.buildTask = () -> task.accept(this);
     }
-    private CompileResult(Scope scope, CompileResult parent) {
+    private CompileResult(Environment env, Scope scope, CompileResult parent) {
         this.scope = scope;
         this.instructions = parent.instructions;
         this.children = parent.children;
         this.map = parent.map;
-        this.env = parent.env;
+        this.env = env;
     }
 }
diff --git a/src/main/java/me/topchetoeu/jscript/compilation/FunctionArrowNode.java b/src/main/java/me/topchetoeu/jscript/compilation/FunctionArrowNode.java
index 83cf64e..d789622 100644
--- a/src/main/java/me/topchetoeu/jscript/compilation/FunctionArrowNode.java
+++ b/src/main/java/me/topchetoeu/jscript/compilation/FunctionArrowNode.java
@@ -4,6 +4,7 @@ import java.util.Arrays;
 
 import me.topchetoeu.jscript.common.Instruction;
 import me.topchetoeu.jscript.common.Instruction.BreakpointType;
+import me.topchetoeu.jscript.common.environment.Environment;
 import me.topchetoeu.jscript.common.parsing.Location;
 import me.topchetoeu.jscript.common.parsing.ParseRes;
 import me.topchetoeu.jscript.common.parsing.Parsing;
@@ -16,7 +17,11 @@ public class FunctionArrowNode extends FunctionNode {
 
     @Override public void compile(CompileResult target, boolean pollute, String name, BreakpointType bp) {
         var id = target.addChild(compileBody(target, name, null));
-        target.add(_i -> Instruction.loadFunc(id, true, false, true, null, captures(id, target)));
+        target.add(_i -> Instruction.loadFunc(id, true, false, true, false, null, captures(id, target)));
+    }
+
+    @Override protected Environment rootEnv(Environment env) {
+        return env.getWith(ClassNode.CLASS_ROOT, () -> super.rootEnv(env));
     }
 
     public FunctionArrowNode(Location loc, Location end, Parameters params, Node body) {
diff --git a/src/main/java/me/topchetoeu/jscript/compilation/FunctionNode.java b/src/main/java/me/topchetoeu/jscript/compilation/FunctionNode.java
index 730cf1f..b4a53b1 100644
--- a/src/main/java/me/topchetoeu/jscript/compilation/FunctionNode.java
+++ b/src/main/java/me/topchetoeu/jscript/compilation/FunctionNode.java
@@ -24,6 +24,10 @@ public abstract class FunctionNode extends Node {
 
     protected void compilePreBody(CompileResult target) { }
 
+    protected Environment rootEnv(Environment env) {
+        return env.get(JavaScript.COMPILE_ROOT);
+    }
+
     public final CompileResult compileBody(Environment env, FunctionScope scope, boolean lastReturn, String _name, String selfName) {
         var name = this.name() != null ? this.name() : _name;
 
@@ -64,7 +68,7 @@ public abstract class FunctionNode extends Node {
         });
     }
     public final CompileResult compileBody(CompileResult parent, String name, String selfName) {
-        return compileBody(parent.env.get(JavaScript.COMPILE_ROOT).child(), new FunctionScope(parent.scope), false, name, selfName);
+        return compileBody(rootEnv(parent.env).child(), new FunctionScope(parent.scope), false, name, selfName);
     }
 
     public abstract void compile(CompileResult target, boolean pollute, String name, BreakpointType bp);
diff --git a/src/main/java/me/topchetoeu/jscript/compilation/FunctionStatementNode.java b/src/main/java/me/topchetoeu/jscript/compilation/FunctionStatementNode.java
index 6de7691..abaee3e 100644
--- a/src/main/java/me/topchetoeu/jscript/compilation/FunctionStatementNode.java
+++ b/src/main/java/me/topchetoeu/jscript/compilation/FunctionStatementNode.java
@@ -17,7 +17,7 @@ public class FunctionStatementNode extends FunctionNode {
 
     @Override public void compile(CompileResult target, boolean pollute, String name, BreakpointType bp) {
         var id = target.addChild(compileBody(target, name, null));
-        target.add(_i -> Instruction.loadFunc(id, true, true, false, name, captures(id, target)));
+        target.add(_i -> Instruction.loadFunc(id, true, true, false, false, name, captures(id, target)));
         target.add(VariableNode.toInit(target, end, this.name));
         if (pollute) target.add(Instruction.pushUndefined());
     }
diff --git a/src/main/java/me/topchetoeu/jscript/compilation/FunctionValueNode.java b/src/main/java/me/topchetoeu/jscript/compilation/FunctionValueNode.java
index db22d72..cf30f75 100644
--- a/src/main/java/me/topchetoeu/jscript/compilation/FunctionValueNode.java
+++ b/src/main/java/me/topchetoeu/jscript/compilation/FunctionValueNode.java
@@ -11,7 +11,7 @@ public class FunctionValueNode extends FunctionNode {
 
     @Override public void compile(CompileResult target, boolean pollute, String name, BreakpointType bp) {
         var id = target.addChild(compileBody(target, name, null));
-        target.add(_i -> Instruction.loadFunc(id, true, true, false, name, captures(id, target)));
+        target.add(_i -> Instruction.loadFunc(id, true, true, false, false, name, captures(id, target)));
     }
 
     public FunctionValueNode(Location loc, Location end, Parameters params, CompoundNode body, String name) {
diff --git a/src/main/java/me/topchetoeu/jscript/compilation/JavaScript.java b/src/main/java/me/topchetoeu/jscript/compilation/JavaScript.java
index d9ddbc9..e9138e1 100644
--- a/src/main/java/me/topchetoeu/jscript/compilation/JavaScript.java
+++ b/src/main/java/me/topchetoeu/jscript/compilation/JavaScript.java
@@ -68,7 +68,7 @@ public final class JavaScript {
         "finally", "for", "do", "while", "switch", "case", "default", "new",
         "function", "var", "return", "throw", "typeof", "delete", "break",
         "continue", "debugger", "implements", "interface", "package", "private",
-        "protected", "public", "static", "arguments", "class"
+        "protected", "public", "static", "arguments", "class", "extends"
     ));
 
     public static ParseRes<? extends Node> parseParens(Source src, int i) {
@@ -130,7 +130,7 @@ public final class JavaScript {
         return ParseRes.failed();
     }
 
-    public static ParseRes<? extends Node> parseExpression(Source src, int i, int precedence, boolean statement) {
+    public static ParseRes<Node> parseExpression(Source src, int i, int precedence, boolean statement) {
         var n = Parsing.skipEmpty(src, i);
         Node prev = null;
 
@@ -174,11 +174,11 @@ public final class JavaScript {
         else return ParseRes.res(prev, n);
     }
 
-    public static ParseRes<? extends Node> parseExpression(Source src, int i, int precedence) {
+    public static ParseRes<Node> parseExpression(Source src, int i, int precedence) {
         return parseExpression(src, i, precedence, false);
     }
 
-    public static ParseRes<? extends Node> parseExpressionStatement(Source src, int i) {
+    public static ParseRes<Node> parseExpressionStatement(Source src, int i) {
         var res = parseExpression(src, i, 0, true);
         if (!res.isSuccess()) return res.chainError();
 
@@ -219,7 +219,7 @@ public final class JavaScript {
 
     public static ParseRes<Boolean> parseStatementEnd(Source src, int i) {
         var n = Parsing.skipEmpty(src, i);
-        if (i >= src.size()) return ParseRes.res(true, n + 1);
+        if (i >= src.size()) return ParseRes.res(true, n);
 
         for (var j = i; j < i + n; j++) {
             if (src.is(j, '\n')) return ParseRes.res(true, n);
diff --git a/src/main/java/me/topchetoeu/jscript/compilation/control/ForOfNode.java b/src/main/java/me/topchetoeu/jscript/compilation/control/ForOfNode.java
index 6438c9f..9bd3108 100644
--- a/src/main/java/me/topchetoeu/jscript/compilation/control/ForOfNode.java
+++ b/src/main/java/me/topchetoeu/jscript/compilation/control/ForOfNode.java
@@ -31,13 +31,12 @@ public class ForOfNode extends Node {
         target.add(Instruction.dup());
         target.add(Instruction.loadIntrinsics("it_key"));
         target.add(Instruction.loadMember()).setLocation(iterable.loc());
-        target.add(Instruction.call(0)).setLocation(iterable.loc());
+        target.add(Instruction.call(0, true)).setLocation(iterable.loc());
 
         int start = target.size();
-        target.add(Instruction.dup());
-        target.add(Instruction.dup());
+        target.add(Instruction.dup(2, 0));
         target.add(Instruction.loadMember("next")).setLocation(iterable.loc());
-        target.add(Instruction.call(0)).setLocation(iterable.loc());
+        target.add(Instruction.call(0, true)).setLocation(iterable.loc());
         target.add(Instruction.dup());
         target.add(Instruction.loadMember("done")).setLocation(iterable.loc());
         int mid = target.temp();
diff --git a/src/main/java/me/topchetoeu/jscript/compilation/control/SwitchNode.java b/src/main/java/me/topchetoeu/jscript/compilation/control/SwitchNode.java
index ee00222..51cb2cc 100644
--- a/src/main/java/me/topchetoeu/jscript/compilation/control/SwitchNode.java
+++ b/src/main/java/me/topchetoeu/jscript/compilation/control/SwitchNode.java
@@ -118,7 +118,6 @@ public class SwitchNode extends Node {
 
         return ParseRes.res(null, n);
     }
-    @SuppressWarnings("unused")
     public static ParseRes<SwitchNode> parse(Source src, int i) {
         var n = Parsing.skipEmpty(src, i);
         var loc = src.loc(i + n);
diff --git a/src/main/java/me/topchetoeu/jscript/compilation/members/MethodMemberNode.java b/src/main/java/me/topchetoeu/jscript/compilation/members/MethodMemberNode.java
index d100366..abc760e 100644
--- a/src/main/java/me/topchetoeu/jscript/compilation/members/MethodMemberNode.java
+++ b/src/main/java/me/topchetoeu/jscript/compilation/members/MethodMemberNode.java
@@ -2,6 +2,7 @@ package me.topchetoeu.jscript.compilation.members;
 
 import me.topchetoeu.jscript.common.Instruction;
 import me.topchetoeu.jscript.common.Instruction.BreakpointType;
+import me.topchetoeu.jscript.common.environment.Environment;
 import me.topchetoeu.jscript.common.parsing.Location;
 import me.topchetoeu.jscript.common.parsing.ParseRes;
 import me.topchetoeu.jscript.common.parsing.Parsing;
@@ -22,12 +23,16 @@ public class MethodMemberNode extends FunctionNode implements Member {
         else return null;
     }
 
+    @Override protected Environment rootEnv(Environment env) {
+        return env;
+    }
+
     @Override public void compile(CompileResult target, boolean pollute, String name, BreakpointType bp) {
         if (pollute) target.add(Instruction.dup());
         key.compile(target, true);
 
         var id = target.addChild(compileBody(target, name, null));
-        target.add(_i -> Instruction.loadFunc(id, true, false, false, name, captures(id, target)));
+        target.add(_i -> Instruction.loadFunc(id, true, false, false, false, null, captures(id, target)));
     }
 
     @Override public void compile(CompileResult target, boolean pollute, boolean enumerable) {
diff --git a/src/main/java/me/topchetoeu/jscript/compilation/members/PropertyMemberNode.java b/src/main/java/me/topchetoeu/jscript/compilation/members/PropertyMemberNode.java
index ff7d748..8290f73 100644
--- a/src/main/java/me/topchetoeu/jscript/compilation/members/PropertyMemberNode.java
+++ b/src/main/java/me/topchetoeu/jscript/compilation/members/PropertyMemberNode.java
@@ -4,6 +4,7 @@ import java.util.Arrays;
 
 import me.topchetoeu.jscript.common.Instruction;
 import me.topchetoeu.jscript.common.Instruction.BreakpointType;
+import me.topchetoeu.jscript.common.environment.Environment;
 import me.topchetoeu.jscript.common.parsing.Location;
 import me.topchetoeu.jscript.common.parsing.ParseRes;
 import me.topchetoeu.jscript.common.parsing.Parsing;
@@ -29,6 +30,10 @@ public class PropertyMemberNode extends FunctionNode implements Member{
         else return null;
     }
 
+    @Override protected Environment rootEnv(Environment env) {
+        return env;
+    }
+
     public boolean isGetter() { return argument == null; }
     public boolean isSetter() { return argument != null; }
 
@@ -37,7 +42,7 @@ public class PropertyMemberNode extends FunctionNode implements Member{
         key.compile(target, true);
 
         var id = target.addChild(compileBody(target, name, null));
-        target.add(_i -> Instruction.loadFunc(id, true, false, false, name, captures(id, target)));
+        target.add(_i -> Instruction.loadFunc(id, true, false, false, false, null, captures(id, target)));
     }
 
 
diff --git a/src/main/java/me/topchetoeu/jscript/compilation/scope/FunctionScope.java b/src/main/java/me/topchetoeu/jscript/compilation/scope/FunctionScope.java
index c5319bc..efd7cc2 100644
--- a/src/main/java/me/topchetoeu/jscript/compilation/scope/FunctionScope.java
+++ b/src/main/java/me/topchetoeu/jscript/compilation/scope/FunctionScope.java
@@ -67,6 +67,21 @@ public class FunctionScope extends Scope {
         return childVar;
     }
 
+    @Override public Variable get(Variable var, boolean capture) {
+        if (captures.has(var)) return addCaptured(var, capture);
+        if (locals.has(var)) return addCaptured(var, capture);
+
+        if (captureParent == null) return null;
+
+        var parentVar = captureParent.get(var, true);
+        if (parentVar == null) return null;
+
+        var childVar = captures.add(parentVar.clone());
+        childToParent.put(childVar, parentVar);
+
+        return childVar;
+    }
+
     @Override public boolean has(String name, boolean capture) {
         if (functionVarMap.containsKey(name)) return true;
         if (specialVarMap.containsKey(name)) return true;
diff --git a/src/main/java/me/topchetoeu/jscript/compilation/scope/Scope.java b/src/main/java/me/topchetoeu/jscript/compilation/scope/Scope.java
index 62de6c0..8d1a476 100644
--- a/src/main/java/me/topchetoeu/jscript/compilation/scope/Scope.java
+++ b/src/main/java/me/topchetoeu/jscript/compilation/scope/Scope.java
@@ -111,6 +111,18 @@ public class Scope {
 
         return null;
     }
+    /**
+     * Gets the index supplier of the given variable, or null if it isn't in this scope chain.
+     * This will also execute capturing logic.
+     *
+     * @param capture If true, the variable is being captured by a function
+     */
+    public Variable get(Variable var, boolean capture) {
+        if (locals.has(var)) return addCaptured(var, capture);
+        if (parent != null) return parent.get(var, capture);
+
+        return null;
+    }
     /**
      * Checks if the given variable name is accessible
      * 
diff --git a/src/main/java/me/topchetoeu/jscript/compilation/scope/VariableList.java b/src/main/java/me/topchetoeu/jscript/compilation/scope/VariableList.java
index 3e71689..5d8dcb5 100644
--- a/src/main/java/me/topchetoeu/jscript/compilation/scope/VariableList.java
+++ b/src/main/java/me/topchetoeu/jscript/compilation/scope/VariableList.java
@@ -64,7 +64,7 @@ public final class VariableList {
     public boolean frozen() {
         if (frozenList != null) {
             assert frozenList != null;
-            assert varMap == null;
+            assert varMap != null;
             assert first == null;
             assert last == null;
 
@@ -139,6 +139,10 @@ public final class VariableList {
         return node.var;
     }
 
+    public boolean has(Variable var) {
+        return varMap.containsKey(var);
+    }
+
     public Supplier<VariableIndex> indexer(Variable var) {
         return varMap.get(var);
     }
@@ -162,7 +166,6 @@ public final class VariableList {
         }
 
         first = last = null;
-        varMap = null;
     }
 
     public Iterable<Variable> all() {
diff --git a/src/main/java/me/topchetoeu/jscript/compilation/values/ClassValueNode.java b/src/main/java/me/topchetoeu/jscript/compilation/values/ClassValueNode.java
index cf4434e..e0240f4 100644
--- a/src/main/java/me/topchetoeu/jscript/compilation/values/ClassValueNode.java
+++ b/src/main/java/me/topchetoeu/jscript/compilation/values/ClassValueNode.java
@@ -5,6 +5,7 @@ import me.topchetoeu.jscript.common.parsing.ParseRes;
 import me.topchetoeu.jscript.common.parsing.Parsing;
 import me.topchetoeu.jscript.common.parsing.Source;
 import me.topchetoeu.jscript.compilation.ClassNode;
+import me.topchetoeu.jscript.compilation.JavaScript;
 
 public class ClassValueNode extends ClassNode {
     public ClassValueNode(Location loc, Location end, String name, ClassBody body) {
@@ -19,10 +20,13 @@ public class ClassValueNode extends ClassNode {
         n += 5;
 
         var name = Parsing.parseIdentifier(src, i + n);
+        if (name.isSuccess() && !JavaScript.checkVarName(name.result)) {
+            name = ParseRes.error(src.loc(i + n), "Unexpected keyword '" + name.result + "'");
+        }
         n += name.n;
 
         var body = parseBody(src, i + n);
-        if (!body.isSuccess()) return body.chainError(src.loc(i + n), "Expected a class body");
+        if (!body.isSuccess()) return body.chainError(name).chainError(src.loc(i + n), "Expected a class body");
         n += body.n;
 
         return ParseRes.res(new ClassValueNode(loc, src.loc(i + n), name.result, body.result), n);
diff --git a/src/main/java/me/topchetoeu/jscript/compilation/values/operations/CallNode.java b/src/main/java/me/topchetoeu/jscript/compilation/values/operations/CallNode.java
index d1414bb..b225827 100644
--- a/src/main/java/me/topchetoeu/jscript/compilation/values/operations/CallNode.java
+++ b/src/main/java/me/topchetoeu/jscript/compilation/values/operations/CallNode.java
@@ -10,12 +10,14 @@ import me.topchetoeu.jscript.common.parsing.Location;
 import me.topchetoeu.jscript.common.parsing.ParseRes;
 import me.topchetoeu.jscript.common.parsing.Parsing;
 import me.topchetoeu.jscript.common.parsing.Source;
+import me.topchetoeu.jscript.compilation.ClassNode;
 import me.topchetoeu.jscript.compilation.CompileResult;
 import me.topchetoeu.jscript.compilation.JavaScript;
 import me.topchetoeu.jscript.compilation.Node;
 import me.topchetoeu.jscript.compilation.values.ArgumentsNode;
 import me.topchetoeu.jscript.compilation.values.ArrayNode;
 import me.topchetoeu.jscript.compilation.values.ObjectNode;
+import me.topchetoeu.jscript.compilation.values.SuperNode;
 import me.topchetoeu.jscript.compilation.values.ThisNode;
 import me.topchetoeu.jscript.compilation.values.VariableNode;
 import me.topchetoeu.jscript.compilation.values.constants.BoolNode;
@@ -88,18 +90,37 @@ public class CallNode extends Node {
     }
 
     @Override public void compile(CompileResult target, boolean pollute, BreakpointType type) {
-        if (!isNew && func instanceof IndexNode) {
-            var obj = ((IndexNode)func).object;
-            var index = ((IndexNode)func).index;
+        var superInstr = target.env.get(ClassNode.SUPER);
+
+        if (!isNew && func instanceof SuperNode && superInstr != null && target.env.hasNotNull(ClassNode.ON_SUPER_CALL)) {
+            target.env.get(ClassNode.SUPER_CONSTR).accept(target);
+            for (var arg : args) arg.compile(target, true);
+            target.add(Instruction.callSuper(args.length));
+            target.env.get(ClassNode.ON_SUPER_CALL).accept(target);
+        }
+        else if (!isNew && func instanceof IndexNode indexn) {
+            var obj = indexn.object;
+            var index = indexn.index;
             String name = "";
 
-            obj.compile(target, true);
-            index.compile(target, true);
+            if (superInstr != null && obj instanceof SuperNode) {
+                new ThisNode(null).compile(target, true);
+                target.env.get(ClassNode.SUPER).accept(target);
+                IndexNode.indexLoad(target, index, true);
+            }
+            else {
+                obj.compile(target, true);
+                target.add(Instruction.dup());
+                IndexNode.indexLoad(target, index, true);
+            }
+
             for (var arg : args) arg.compile(target, true);
 
             if (ATTACH_NAME) name = generateName(obj, index);
 
-            target.add(Instruction.callMember(args.length, name)).setLocationAndDebug(loc(), type);
+            target.add(Instruction.call(args.length, true, name));
+
+            target.setLocationAndDebug(loc(), type);
         }
         else {
             String name = "";
@@ -110,7 +131,7 @@ public class CallNode extends Node {
             if (ATTACH_NAME) name = generateName(func, null);
 
             if (isNew) target.add(Instruction.callNew(args.length, name)).setLocationAndDebug(loc(), type);
-            else target.add(Instruction.call(args.length, name)).setLocationAndDebug(loc(), type);
+            else target.add(Instruction.call(args.length, false, name)).setLocationAndDebug(loc(), type);
         }
         if (!pollute) target.add(Instruction.discard());
     }
diff --git a/src/main/java/me/topchetoeu/jscript/compilation/values/operations/IndexNode.java b/src/main/java/me/topchetoeu/jscript/compilation/values/operations/IndexNode.java
index 826b8cd..752e9a9 100644
--- a/src/main/java/me/topchetoeu/jscript/compilation/values/operations/IndexNode.java
+++ b/src/main/java/me/topchetoeu/jscript/compilation/values/operations/IndexNode.java
@@ -6,10 +6,12 @@ import me.topchetoeu.jscript.common.parsing.Location;
 import me.topchetoeu.jscript.common.parsing.ParseRes;
 import me.topchetoeu.jscript.common.parsing.Parsing;
 import me.topchetoeu.jscript.common.parsing.Source;
+import me.topchetoeu.jscript.compilation.ClassNode;
 import me.topchetoeu.jscript.compilation.CompileResult;
 import me.topchetoeu.jscript.compilation.JavaScript;
 import me.topchetoeu.jscript.compilation.Node;
 import me.topchetoeu.jscript.compilation.patterns.ChangeTarget;
+import me.topchetoeu.jscript.compilation.values.SuperNode;
 import me.topchetoeu.jscript.compilation.values.constants.NumberNode;
 import me.topchetoeu.jscript.compilation.values.constants.StringNode;
 
@@ -18,12 +20,11 @@ public class IndexNode extends Node implements ChangeTarget {
     public final Node index;
 
     @Override public void beforeAssign(CompileResult target) {
-        object.compile(target, true);
-
+        compileObj(target, object);
         indexStorePushKey(target, index);
     }
     @Override public void beforeChange(CompileResult target) {
-        object.compile(target, true);
+        compileObj(target, object);
 
         if (index instanceof NumberNode num && (int)num.value == num.value) {
             target.add(Instruction.dup());
@@ -43,7 +44,7 @@ public class IndexNode extends Node implements ChangeTarget {
     }
 
     @Override public void assign(CompileResult target, boolean pollute) {
-        object.compile(target, true);
+        compileObj(target, object);
         target.add(Instruction.dup(1, 1));
         indexStorePushKey(target, index);
         indexStore(target, index, pollute);
@@ -54,7 +55,7 @@ public class IndexNode extends Node implements ChangeTarget {
     }
 
     public void compile(CompileResult target, boolean dupObj, boolean pollute) {
-        object.compile(target, true);
+        compileObj(target, object);
         if (dupObj) target.add(Instruction.dup());
 
         if (index instanceof NumberNode num && (int)num.value == num.value) {
@@ -82,6 +83,13 @@ public class IndexNode extends Node implements ChangeTarget {
         this.index = index;
     }
 
+    private static void compileObj(CompileResult target, Node obj) {
+        if (obj instanceof SuperNode && target.env.hasNotNull(ClassNode.SUPER)) {
+            target.env.get(ClassNode.SUPER).accept(target);
+        }
+        else obj.compile(target, true);
+    }
+
     public static ParseRes<IndexNode> parseIndex(Source src, int i, Node prev, int precedence) {
         if (precedence > 18) return ParseRes.failed();
 
diff --git a/src/main/java/me/topchetoeu/jscript/runtime/EventLoop.java b/src/main/java/me/topchetoeu/jscript/runtime/EventLoop.java
index 6a929a0..6126684 100644
--- a/src/main/java/me/topchetoeu/jscript/runtime/EventLoop.java
+++ b/src/main/java/me/topchetoeu/jscript/runtime/EventLoop.java
@@ -28,9 +28,9 @@ public interface EventLoop {
     }
 
     public default Future<Value> pushMsg(boolean micro, Environment env, FunctionValue func, Value thisArg, Value ...args) {
-        return pushMsg(() -> func.invoke(env, thisArg, args), micro);
+        return pushMsg(() -> func.apply(env, thisArg, args), micro);
     }
     public default Future<Value> pushMsg(boolean micro, Environment env, Filename filename, String raw, Value thisArg, Value ...args) {
-        return pushMsg(() -> Compiler.compileFunc(env, filename, raw).invoke(env, thisArg, args), micro);
+        return pushMsg(() -> Compiler.compileFunc(env, filename, raw).apply(env, thisArg, args), micro);
     }
 }
diff --git a/src/main/java/me/topchetoeu/jscript/runtime/Frame.java b/src/main/java/me/topchetoeu/jscript/runtime/Frame.java
index 17e5a2c..636a881 100644
--- a/src/main/java/me/topchetoeu/jscript/runtime/Frame.java
+++ b/src/main/java/me/topchetoeu/jscript/runtime/Frame.java
@@ -15,6 +15,11 @@ import me.topchetoeu.jscript.runtime.values.objects.ObjectValue;
 
 public final class Frame {
     public static final Key<Frame> KEY = Key.of();
+    public static final EngineException STACK_OVERFLOW;
+    static {
+        STACK_OVERFLOW = EngineException.ofRange("Stack overflow!");
+        STACK_OVERFLOW.value.freeze();
+    }
 
     public static enum TryState {
         TRY,
@@ -193,6 +198,7 @@ public final class Frame {
                     }
                 }
             }
+            catch (StackOverflowError e) { throw STACK_OVERFLOW; }
             catch (EngineException e) { error = e; }
             catch (RuntimeException e) {
                 System.out.println(dbg.getMapOrEmpty(function).toLocation(codePtr, true));
@@ -268,6 +274,13 @@ public final class Frame {
             }
         }
 
+        if (returnValue != null) {
+            if (self == null) error = EngineException.ofError("Super constructor must be called before returning");
+            else {
+                dbg.onInstruction(env, this, instr, returnValue, null, false);
+                return returnValue;
+            }
+        }
         if (error != null) {
             var caught = false;
 
@@ -280,10 +293,6 @@ public final class Frame {
             dbg.onInstruction(env, this, instr, null, error, caught);
             throw error;
         }
-        if (returnValue != null) {
-            dbg.onInstruction(env, this, instr, returnValue, null, false);
-            return returnValue;
-        }
 
         return null;
     }
diff --git a/src/main/java/me/topchetoeu/jscript/runtime/InstructionRunner.java b/src/main/java/me/topchetoeu/jscript/runtime/InstructionRunner.java
index 8bdc6dd..10d1b15 100644
--- a/src/main/java/me/topchetoeu/jscript/runtime/InstructionRunner.java
+++ b/src/main/java/me/topchetoeu/jscript/runtime/InstructionRunner.java
@@ -32,18 +32,22 @@ public class InstructionRunner {
     private static Value execCall(Environment env, Instruction instr, Frame frame) {
         var callArgs = frame.take(instr.get(0));
         var func = frame.pop();
+        var self = (boolean)instr.get(1) ? frame.pop() : Value.UNDEFINED;
 
-        frame.push(func.call(env, false, instr.get(1), Value.UNDEFINED, callArgs));
+        frame.push(func.apply(env, instr.get(2), self, callArgs));
 
         frame.codePtr++;
         return null;
     }
-    private static Value execCallMember(Environment env, Instruction instr, Frame frame) {
+    private static Value execCallSuper(Environment env, Instruction instr, Frame frame) {
         var callArgs = frame.take(instr.get(0));
-        var index = frame.pop();
-        var obj = frame.pop();
+        var superFunc = frame.pop();
 
-        frame.push(obj.getMember(env, index).call(env, false, instr.get(1), obj, callArgs));
+        var self = new ObjectValue();
+        if (frame.function.prototype instanceof ObjectValue objProto) self.setPrototype(env, objProto);
+
+        frame.self = superFunc.construct(env, "super", self, callArgs);
+        frame.push(frame.self);
 
         frame.codePtr++;
         return null;
@@ -185,11 +189,12 @@ public class InstructionRunner {
         boolean callable = instr.get(2);
         boolean constructible = instr.get(3);
         boolean captureThis = instr.get(4);
-    
-        var captures = new Value[instr.params.length - 5][];
+        boolean noThis = instr.get(5);
 
-        for (var i = 5; i < instr.params.length; i++) {
-            captures[i - 5] = frame.captureVar(instr.get(i));
+        var captures = new Value[instr.params.length - 6][];
+
+        for (var i = 6; i < instr.params.length; i++) {
+            captures[i - 6] = frame.captureVar(instr.get(i));
         }
 
         var func = new CodeFunction(env, name, frame.function.body.children[id], captures);
@@ -199,6 +204,8 @@ public class InstructionRunner {
             func.self = frame.self;
             func.argsVal = frame.argsVal;
         }
+        if (noThis) func.mustCallSuper = true;
+
         frame.push(func);
 
         frame.codePtr++;
@@ -487,6 +494,20 @@ public class InstructionRunner {
         frame.codePtr++;
         return null;
     }
+    private static Value execExtend(Environment env, Instruction instr, Frame frame) {
+        var superVal = frame.peek(0);
+        var derivedVal = frame.peek(1);
+
+        if (!(superVal instanceof FunctionValue superFunc)) throw EngineException.ofType("Illegal EXTENDS instruction");
+        if (!(superFunc.prototype instanceof ObjectValue superProto)) throw EngineException.ofType("Illegal EXTENDS instruction");
+        if (!(derivedVal instanceof FunctionValue derivedFunc)) throw EngineException.ofType("Illegal EXTENDS instruction");
+
+        derivedFunc.setPrototype(env, superFunc);
+        derivedFunc.prototype.setPrototype(env, superProto);
+
+        frame.codePtr++;
+        return null;
+    }
 
     private static Value execLoadArgs(Environment env, Instruction instr, Frame frame) {
         if ((boolean)instr.get(0) || frame.fakeArgs == null) frame.push(frame.argsVal);
@@ -510,6 +531,7 @@ public class InstructionRunner {
         return null;
     }
     private static Value execLoadThis(Environment env, Instruction instr, Frame frame) {
+        if (frame.self == null) throw EngineException.ofError("Super constructor must be called before 'this' is accessed");
         frame.push(frame.self);
         frame.codePtr++;
         return null;
@@ -547,7 +569,7 @@ public class InstructionRunner {
             case THROW_SYNTAX: return execThrowSyntax(env, instr, frame);
             case CALL: return execCall(env, instr, frame);
             case CALL_NEW: return execCallNew(env, instr, frame);
-            case CALL_MEMBER: return execCallMember(env, instr, frame);
+            case CALL_SUPER: return execCallSuper(env, instr, frame);
             case TRY_START: return execTryStart(env, instr, frame);
             case TRY_END: return execTryEnd(env, instr, frame);
 
@@ -595,6 +617,7 @@ public class InstructionRunner {
             case GLOB_DEF: return exexGlobDef(env, instr, frame);
             case GLOB_GET: return exexGlobGet(env, instr, frame);
             case GLOB_SET: return exexGlobSet(env, instr, frame);
+            case EXTEND: return execExtend(env, instr, frame);
 
             case VAR_INIT: return execVarInit(env, instr, frame);
             case VAR_FREE: return execVarFree(env, instr, frame);
diff --git a/src/main/java/me/topchetoeu/jscript/runtime/SimpleRepl.java b/src/main/java/me/topchetoeu/jscript/runtime/SimpleRepl.java
index 5518ec7..b6047dc 100644
--- a/src/main/java/me/topchetoeu/jscript/runtime/SimpleRepl.java
+++ b/src/main/java/me/topchetoeu/jscript/runtime/SimpleRepl.java
@@ -231,7 +231,7 @@ public class SimpleRepl {
             var funcArgs = (ArrayValue)args.get(2);
             var name = args.get(3).toString(env);
 
-            return func.invoke(env, name, self, funcArgs.toArray());
+            return func.apply(env, name, self, funcArgs.toArray());
         }));
         res.defineOwnMember(env, "construct", new NativeFunction(args -> {
             var func = (FunctionValue)args.get(0);
@@ -263,7 +263,7 @@ public class SimpleRepl {
             var self = args.get(1);
             var funcArgs = (ArrayValue)args.get(2);
 
-            return func.invoke(env, self, funcArgs.toArray());
+            return func.apply(env, self, funcArgs.toArray());
         }));
 
         return res;
@@ -362,7 +362,7 @@ public class SimpleRepl {
         glob.defineOwnMember(null, "measure", new NativeFunction("measure", args -> {
             var start = System.nanoTime();
 
-            ((FunctionValue)args.get(0)).invoke(args.env, Value.UNDEFINED);
+            ((FunctionValue)args.get(0)).apply(args.env, Value.UNDEFINED);
 
             System.out.println(String.format("Finished in %sns", System.nanoTime() - start));
 
diff --git a/src/main/java/me/topchetoeu/jscript/runtime/values/Value.java b/src/main/java/me/topchetoeu/jscript/runtime/values/Value.java
index 2979392..817ef2d 100644
--- a/src/main/java/me/topchetoeu/jscript/runtime/values/Value.java
+++ b/src/main/java/me/topchetoeu/jscript/runtime/values/Value.java
@@ -89,7 +89,7 @@ public abstract class Value {
         else throw EngineException.ofType(name + " is not a function");
     }
 
-    public final Value invoke(Environment env, String name, Value self, Value ...args) {
+    public final Value apply(Environment env, String name, Value self, Value ...args) {
         return call(env, false, name, self, args);
     }
     public final Value construct(Environment env, String name, Value ...args) {
@@ -97,16 +97,19 @@ public abstract class Value {
         var proto = getMember(env, StringValue.of("prototype"));
 
         if (proto instanceof ObjectValue) res.setPrototype(env, (ObjectValue)proto);
-        else res.setPrototype(env, null);
 
         var ret = this.call(env, true, name, res, args);
 
         if (!ret.isPrimitive()) return ret;
         return res;
     }
+    public final Value construct(Environment env, String name, Value self, Value ...args) {
+        var ret = this.call(env, true, name, self, args);
+        return ret.isPrimitive() ? self : ret;
+    }
 
-    public final Value invoke(Environment env, Value self, Value ...args) {
-        return invoke(env, "", self, args);
+    public final Value apply(Environment env, Value self, Value ...args) {
+        return apply(env, "", self, args);
     }
     public final Value construct(Environment env, Value ...args) {
         return construct(env, "", args);
@@ -118,7 +121,7 @@ public abstract class Value {
     public abstract boolean toBoolean();
 
     public final boolean isInstanceOf(Environment env, Value proto) {
-        for (var val = getPrototype(env); val != null; val = getPrototype(env)) {
+        for (var val = getPrototype(env); val != null; val = val.getPrototype(env)) {
             if (val.equals(proto)) return true;
         }
 
@@ -390,7 +393,7 @@ public abstract class Value {
                 private void loadNext() {
                     if (supplier == null) value = null;
                     else if (consumed) {
-                        var curr = supplier.invoke(env, Value.UNDEFINED);
+                        var curr = supplier.apply(env, Value.UNDEFINED);
 
                         if (curr == null) { supplier = null; value = null; }
                         if (curr.getMember(env, StringValue.of("done")).toBoolean()) { supplier = null; value = null; }
@@ -418,12 +421,12 @@ public abstract class Value {
 
     public void callWith(Environment env, Iterable<? extends Value> it) {
         for (var el : it) {
-            this.invoke(env, Value.UNDEFINED, el);
+            this.apply(env, Value.UNDEFINED, el);
         }
     }
     public void callWithAsync(Environment env, Iterable<? extends Value> it, boolean async) {
         for (var el : it) {
-            env.get(EventLoop.KEY).pushMsg(() -> this.invoke(env, Value.UNDEFINED, el), true);
+            env.get(EventLoop.KEY).pushMsg(() -> this.apply(env, Value.UNDEFINED, el), true);
         }
     }
 
diff --git a/src/main/java/me/topchetoeu/jscript/runtime/values/functions/CodeFunction.java b/src/main/java/me/topchetoeu/jscript/runtime/values/functions/CodeFunction.java
index 7d900fa..5bf781e 100644
--- a/src/main/java/me/topchetoeu/jscript/runtime/values/functions/CodeFunction.java
+++ b/src/main/java/me/topchetoeu/jscript/runtime/values/functions/CodeFunction.java
@@ -8,11 +8,13 @@ import me.topchetoeu.jscript.runtime.values.Value;
 public final class CodeFunction extends FunctionValue {
     public final FunctionBody body;
     public final Value[][] captures;
-    public Value self;
-    public Value argsVal;
     public Environment env;
 
+    public Value self;
+    public Value argsVal;
+
     private Value onCall(Frame frame) {
+        if (mustCallSuper) frame.self = null;
         frame.onPush();
 
         try {
@@ -31,7 +33,10 @@ public final class CodeFunction extends FunctionValue {
         if (argsVal != null) frame.fakeArgs = argsVal;
         if (self != null) frame.self = self;
 
-        return onCall(frame);
+        var res = onCall(frame);
+
+        if (isNew) return frame.self;
+        else return res;
     }
 
     public CodeFunction(Environment env, String name, FunctionBody body, Value[][] captures) {
diff --git a/src/main/java/me/topchetoeu/jscript/runtime/values/functions/FunctionValue.java b/src/main/java/me/topchetoeu/jscript/runtime/values/functions/FunctionValue.java
index 6bfbb8d..b44c76b 100644
--- a/src/main/java/me/topchetoeu/jscript/runtime/values/functions/FunctionValue.java
+++ b/src/main/java/me/topchetoeu/jscript/runtime/values/functions/FunctionValue.java
@@ -23,6 +23,7 @@ public abstract class FunctionValue extends ObjectValue {
 
     public boolean enableCall = true;
     public boolean enableNew = true;
+    public boolean mustCallSuper = false;
 
     private final FieldMember nameField = new FieldMember(this, true, false, false) {
         @Override public Value get(Environment env, Value self) {
diff --git a/src/main/java/me/topchetoeu/jscript/runtime/values/objects/ObjectValue.java b/src/main/java/me/topchetoeu/jscript/runtime/values/objects/ObjectValue.java
index 616b775..12e67b0 100644
--- a/src/main/java/me/topchetoeu/jscript/runtime/values/objects/ObjectValue.java
+++ b/src/main/java/me/topchetoeu/jscript/runtime/values/objects/ObjectValue.java
@@ -46,13 +46,13 @@ public class ObjectValue extends Value {
             var valueOf = getMember(env, "valueOf");
 
             if (valueOf instanceof FunctionValue) {
-                var res = valueOf.invoke(env, this);
+                var res = valueOf.apply(env, this);
                 if (res.isPrimitive()) return res;
             }
 
             var toString = getMember(env, "toString");
             if (toString instanceof FunctionValue) {
-                var res = toString.invoke(env, this);
+                var res = toString.apply(env, this);
                 if (res.isPrimitive()) return res;
             }
         }
diff --git a/src/main/resources/lib/index.js b/src/main/resources/lib/index.js
index e2f8af6..1d02395 100644
--- a/src/main/resources/lib/index.js
+++ b/src/main/resources/lib/index.js
@@ -241,7 +241,6 @@ target.Boolean = Boolean;
 
 class Object {
     toString() {
-        print("2");
         if (this !== null && this !== undefined && (Symbol.toStringTag in this)) return "[object " + this[Symbol.toStringTag] + "]";
         else if (typeof this === "number" || this instanceof Number) return "[object Number]";
         else if (typeof this === "symbol" || this instanceof Symbol) return "[object Symbol]";
@@ -251,13 +250,11 @@ class Object {
         else return "[object Object]";
     }
     valueOf() {
-        print("1");
         return this;
     }
 
     constructor(value) {
         if (typeof value === 'object' && value !== null) return value;
-
         if (typeof value === 'string') return new String(value);
         if (typeof value === 'number') return new Number(value);
         if (typeof value === 'boolean') return new Boolean(value);
@@ -268,19 +265,15 @@ class Object {
             return res;
         }
 
-        const target = this;
-        // TODO: use new.target.prototype as proto
-        if (target == null || typeof target !== 'object') target = {};
+        return {};
+        // // TODO: use new.target.prototype as proto
+        // if (target == null || typeof target !== 'object') target = {};
 
-        this[valueKey] = Object(value);
+        // return target;
     }
 
     static defineProperty(obj, key, desc) {
-        if (typeof obj !== "object" || obj === null) {
-            print(obj);
-            print(typeof obj);
-            throw new TypeError("Object.defineProperty called on non-object");
-        }
+        if (typeof obj !== "object" || obj === null) throw new TypeError("Object.defineProperty called on non-object");
         if (typeof desc !== "object" || desc === null) throw new TypeError("Property description must be an object: " + desc);
 
         if ("get" in desc || "set" in desc) {