diff --git a/src/java/me/topchetoeu/jscript/common/FunctionBody.java b/src/java/me/topchetoeu/jscript/common/FunctionBody.java
index 9d3cab1..3b91614 100644
--- a/src/java/me/topchetoeu/jscript/common/FunctionBody.java
+++ b/src/java/me/topchetoeu/jscript/common/FunctionBody.java
@@ -3,10 +3,11 @@ package me.topchetoeu.jscript.common;
 public class FunctionBody {
     public final FunctionBody[] children;
     public final Instruction[] instructions;
-    public final int localsN, capturesN, argsN;
+    public final int localsN, capturesN, argsN, length;
 
-    public FunctionBody(int localsN, int capturesN, int argsN, Instruction[] instructions, FunctionBody[] children) {
+    public FunctionBody(int localsN, int capturesN, int length, int argsN, Instruction[] instructions, FunctionBody[] children) {
         this.children = children;
+        this.length = length;
         this.argsN = argsN;
         this.localsN = localsN;
         this.capturesN = capturesN;
diff --git a/src/java/me/topchetoeu/jscript/compilation/CompileResult.java b/src/java/me/topchetoeu/jscript/compilation/CompileResult.java
index 59ce8fd..0a78253 100644
--- a/src/java/me/topchetoeu/jscript/compilation/CompileResult.java
+++ b/src/java/me/topchetoeu/jscript/compilation/CompileResult.java
@@ -3,7 +3,7 @@ package me.topchetoeu.jscript.compilation;
 import java.util.List;
 import java.util.ArrayList;
 import java.util.LinkedList;
-import java.util.function.Supplier;
+import java.util.function.IntFunction;
 
 import me.topchetoeu.jscript.common.FunctionBody;
 import me.topchetoeu.jscript.common.Instruction;
@@ -16,11 +16,11 @@ import me.topchetoeu.jscript.compilation.scope.LocalScope;
 import me.topchetoeu.jscript.compilation.scope.Scope;
 
 public final class CompileResult {
-    public final List<Supplier<Instruction>> instructions;
+    public final List<IntFunction<Instruction>> instructions;
     public final List<CompileResult> children;
     public final FunctionMapBuilder map;
     public final Environment env;
-    public int length = 0;
+    public int length, assignN;
     public final Scope scope;
 
     public int temp() {
@@ -29,18 +29,18 @@ public final class CompileResult {
     }
 
     public CompileResult add(Instruction instr) {
-        instructions.add(() -> instr);
+        instructions.add(i -> instr);
         return this;
     }
-    public CompileResult add(Supplier<Instruction> instr) {
+    public CompileResult add(IntFunction<Instruction> instr) {
         instructions.add(instr);
         return this;
     }
     public CompileResult set(int i, Instruction instr) {
-        instructions.set(i, () -> instr);
+        instructions.set(i, _i -> instr);
         return this;
     }
-    public CompileResult set(int i, Supplier<Instruction>instr) {
+    public CompileResult set(int i, IntFunction<Instruction>instr) {
         instructions.set(i, instr);
         return this;
     }
@@ -76,7 +76,10 @@ public final class CompileResult {
     public Instruction[] instructions() {
         var res = new Instruction[instructions.size()];
         var i = 0;
-        for (var suppl : instructions) res[i++] = suppl.get();
+        for (var suppl : instructions) {
+            res[i] = suppl.apply(i);
+            i++;
+        }
         return res;
     }
 
@@ -90,10 +93,15 @@ public final class CompileResult {
 
         var instrRes = new Instruction[instructions.size()];
         var i = 0;
-        for (var suppl : instructions) instrRes[i++] = suppl.get();
+
+        for (var suppl : instructions) {
+            instrRes[i] = suppl.apply(i);
+            i++;
+        }
 
         return new FunctionBody(
-            scope.localsCount() + scope.allocCount(), scope.capturesCount(), length,
+            scope.localsCount() + scope.allocCount(), scope.capturesCount(),
+            length, assignN,
             instrRes, builtChildren
         );
     }
diff --git a/src/java/me/topchetoeu/jscript/compilation/CompoundNode.java b/src/java/me/topchetoeu/jscript/compilation/CompoundNode.java
index a45f58b..0a03de1 100644
--- a/src/java/me/topchetoeu/jscript/compilation/CompoundNode.java
+++ b/src/java/me/topchetoeu/jscript/compilation/CompoundNode.java
@@ -19,11 +19,11 @@ public class CompoundNode extends Node {
         for (var stm : statements) stm.resolve(target);
     }
 
-    @Override public void compile(CompileResult target, boolean pollute, BreakpointType type) {
+    public void compile(CompileResult target, boolean pollute, boolean alloc, BreakpointType type) {
         List<Node> statements = new ArrayList<Node>();
 
         var subtarget = target.subtarget();
-        subtarget.add(() -> Instruction.stackAlloc(subtarget.scope.allocCount()));
+        if (alloc) subtarget.add(i -> Instruction.stackAlloc(subtarget.scope.allocCount()));
 
         for (var stm : this.statements) {
             if (stm instanceof FunctionStatementNode func) {
@@ -42,13 +42,17 @@ public class CompoundNode extends Node {
         }
 
         subtarget.scope.end();
-        subtarget.add(Instruction.stackFree(subtarget.scope.allocCount()));
+        if (alloc) subtarget.add(Instruction.stackFree(subtarget.scope.allocCount()));
 
         if (!polluted && pollute) {
             target.add(Instruction.pushUndefined());
         }
     }
 
+    @Override public void compile(CompileResult target, boolean pollute, BreakpointType type) {
+        compile(target, pollute, true, type);
+    }
+
     public CompoundNode setEnd(Location loc) {
         this.end = loc;
         return this;
diff --git a/src/java/me/topchetoeu/jscript/compilation/FunctionNode.java b/src/java/me/topchetoeu/jscript/compilation/FunctionNode.java
index ed54d94..66c88e4 100644
--- a/src/java/me/topchetoeu/jscript/compilation/FunctionNode.java
+++ b/src/java/me/topchetoeu/jscript/compilation/FunctionNode.java
@@ -1,6 +1,7 @@
 package me.topchetoeu.jscript.compilation;
 
 import me.topchetoeu.jscript.common.Instruction;
+import me.topchetoeu.jscript.common.Operation;
 import me.topchetoeu.jscript.common.Instruction.BreakpointType;
 import me.topchetoeu.jscript.common.parsing.Location;
 import me.topchetoeu.jscript.common.parsing.ParseRes;
@@ -12,7 +13,7 @@ import me.topchetoeu.jscript.runtime.exceptions.SyntaxException;
 
 public abstract class FunctionNode extends Node {
     public final CompoundNode body;
-    public final String[] args;
+    public final Parameters params;
     public final Location end;
 
     public abstract String name();
@@ -39,14 +40,6 @@ public abstract class FunctionNode extends Node {
     }
 
     private CompileResult compileBody(CompileResult target, String name, boolean storeSelf, boolean pollute, BreakpointType bp) {
-        for (var i = 0; i < args.length; i++) {
-            for (var j = 0; j < i; j++) {
-                if (args[i].equals(args[j])) {
-                    throw new SyntaxException(loc(), "Duplicate parameter '" + args[i] + "'.");
-                }
-            }
-        }
-
         var env = target.env.child()
             .remove(LabelContext.BREAK_CTX)
             .remove(LabelContext.CONTINUE_CTX);
@@ -54,16 +47,31 @@ public abstract class FunctionNode extends Node {
         var funcScope = new FunctionScope(target.scope);
         var subtarget = new CompileResult(env, new LocalScope(funcScope));
 
-        for (var arg : args) {
+        for (var param : params.params) {
             // TODO: Implement default values
             // TODO: Implement argument location
-            funcScope.defineArg(arg, loc());
+            if (funcScope.hasArg(param.name)) throw new SyntaxException(param.loc, "Duplicate parameter name not allowed");
+            var i = funcScope.defineParam(param.name, param.loc);
+
+            if (param.node != null) {
+                var end = new DeferredIntSupplier();
+
+                subtarget.add(_i -> Instruction.loadVar(i.index()));
+                subtarget.add(Instruction.pushUndefined());
+                subtarget.add(Instruction.operation(Operation.EQUALS));
+                subtarget.add(_i -> Instruction.jmpIfNot(end.getAsInt() - _i));
+                param.node.compile(subtarget, pollute);
+                subtarget.add(_i -> Instruction.storeVar(i.index()));
+
+                end.set(subtarget.size());
+            }
         }
 
         body.resolve(subtarget);
-        body.compile(subtarget, false);
+        body.compile(subtarget, false, false, BreakpointType.NONE);
 
-        subtarget.length = args.length;
+        subtarget.length = params.length;
+        subtarget.assignN = params.params.size();
         subtarget.scope.end();
         funcScope.end();
 
@@ -88,11 +96,11 @@ public abstract class FunctionNode extends Node {
         compile(target, pollute, (String)null, BreakpointType.NONE);
     }
 
-    public FunctionNode(Location loc, Location end, String[] args, CompoundNode body) {
+    public FunctionNode(Location loc, Location end, Parameters params, CompoundNode body) {
         super(loc);
 
         this.end = end;
-        this.args = args;
+        this.params = params;
         this.body = body;
     }
 
@@ -117,21 +125,21 @@ public abstract class FunctionNode extends Node {
         n += name.n;
         n += Parsing.skipEmpty(src, i + n);
 
-        var args = JavaScript.parseParamList(src, i + n);
-        if (!args.isSuccess()) return args.chainError(src.loc(i + n), "Expected a parameter list");
-        n += args.n;
+        var params = JavaScript.parseParameters(src, i + n);
+        if (!params.isSuccess()) return params.chainError(src.loc(i + n), "Expected a parameter list");
+        n += params.n;
 
         var body = CompoundNode.parse(src, i + n);
-        if (!body.isSuccess()) return body.chainError(src.loc(i + n), "Expected a compound statement for function.");
+        if (!body.isSuccess()) return body.chainError(src.loc(i + n), "Expected a compound statement for function");
         n += body.n;
 
         if (statement) return ParseRes.res(new FunctionStatementNode(
             loc, src.loc(i + n - 1),
-            args.result.toArray(String[]::new), body.result, name.result
+            params.result, body.result, name.result
         ), n);
         else return ParseRes.res(new FunctionValueNode(
             loc, src.loc(i + n - 1),
-            args.result.toArray(String[]::new), body.result, name.result
+            params.result, body.result, name.result
         ), n);
     }
 }
diff --git a/src/java/me/topchetoeu/jscript/compilation/FunctionStatementNode.java b/src/java/me/topchetoeu/jscript/compilation/FunctionStatementNode.java
index 1b404f3..183fcd9 100644
--- a/src/java/me/topchetoeu/jscript/compilation/FunctionStatementNode.java
+++ b/src/java/me/topchetoeu/jscript/compilation/FunctionStatementNode.java
@@ -18,8 +18,8 @@ public class FunctionStatementNode extends FunctionNode {
         target.add(VariableNode.toSet(target, end, this.name, pollute, true));
     }
 
-    public FunctionStatementNode(Location loc, Location end, String[] args, CompoundNode body, String name) {
-        super(loc, end, args, body);
+    public FunctionStatementNode(Location loc, Location end, Parameters params, CompoundNode body, String name) {
+        super(loc, end, params, body);
         this.name = name;
     }
 }
diff --git a/src/java/me/topchetoeu/jscript/compilation/FunctionValueNode.java b/src/java/me/topchetoeu/jscript/compilation/FunctionValueNode.java
index c89d48d..89f96dd 100644
--- a/src/java/me/topchetoeu/jscript/compilation/FunctionValueNode.java
+++ b/src/java/me/topchetoeu/jscript/compilation/FunctionValueNode.java
@@ -12,8 +12,8 @@ public class FunctionValueNode extends FunctionNode {
         compile(target, pollute, true, name, bp);
     }
 
-    public FunctionValueNode(Location loc, Location end, String[] args, CompoundNode body, String name) {
-        super(loc, end, args, body);
+    public FunctionValueNode(Location loc, Location end, Parameters params, CompoundNode body, String name) {
+        super(loc, end, params, body);
         this.name = name;
     }
 }
diff --git a/src/java/me/topchetoeu/jscript/compilation/JavaScript.java b/src/java/me/topchetoeu/jscript/compilation/JavaScript.java
index 96f2bbb..7b58aae 100644
--- a/src/java/me/topchetoeu/jscript/compilation/JavaScript.java
+++ b/src/java/me/topchetoeu/jscript/compilation/JavaScript.java
@@ -1,10 +1,10 @@
 package me.topchetoeu.jscript.compilation;
 
 import java.util.ArrayList;
-import java.util.List;
 import java.util.Set;
 
 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.Filename;
 import me.topchetoeu.jscript.common.parsing.ParseRes;
@@ -212,40 +212,53 @@ public class JavaScript {
         return ParseRes.failed();
     }
 
-    public static ParseRes<List<String>> parseParamList(Source src, int i) {
+    public static ParseRes<Parameters> parseParameters(Source src, int i) {
         var n = Parsing.skipEmpty(src, i);
 
         var openParen = Parsing.parseOperator(src, i + n, "(");
-        if (!openParen.isSuccess()) return openParen.chainError(src.loc(i + n), "Expected a parameter list.");
+        if (!openParen.isSuccess()) return openParen.chainError(src.loc(i + n), "Expected a parameter list");
         n += openParen.n;
 
-        var args = new ArrayList<String>();
+        var params = new ArrayList<Parameter>();
 
         var closeParen = Parsing.parseOperator(src, i + n, ")");
         n += closeParen.n;
 
         if (!closeParen.isSuccess()) {
             while (true) {
-                var argRes = Parsing.parseIdentifier(src, i + n);
-                if (argRes.isSuccess()) {
-                    args.add(argRes.result);
-                    n += argRes.n;
-                    n += Parsing.skipEmpty(src, i);
+                n += Parsing.skipEmpty(src, i + n);
 
-                    if (src.is(i + n, ",")) {
-                        n++;
-                        n += Parsing.skipEmpty(src, i + n);
-                    }
-                    if (src.is(i + n, ")")) {
-                        n++;
-                        break;
-                    }
+                var paramLoc = src.loc(i);
+
+                var name = Parsing.parseIdentifier(src, i + n);
+                if (!name.isSuccess()) return ParseRes.error(src.loc(i + n), "Expected an argument or a closing brace");
+                n += name.n;
+                n += Parsing.skipEmpty(src, i + n);
+
+                if (src.is(i + n, "=")) {
+                    n++;
+
+                    var val = parseExpression(src, i + n, 2);
+                    if (!val.isSuccess()) return openParen.chainError(src.loc(i + n), "Expected a default value");
+                    n += val.n;
+                    n += Parsing.skipEmpty(src, i + n);
+
+                    params.add(new Parameter(paramLoc, name.result, val.result));
+                }
+                else params.add(new Parameter(paramLoc, name.result, null));
+
+                if (src.is(i + n, ",")) {
+                    n++;
+                    n += Parsing.skipEmpty(src, i + n);
+                }
+                if (src.is(i + n, ")")) {
+                    n++;
+                    break;
                 }
-                else return ParseRes.error(src.loc(i + n), "Expected an argument, or a closing brace.");
             }
         }
 
-        return ParseRes.res(args, n);
+        return ParseRes.res(new Parameters(params), n);
     }
 
     public static Node[] parse(Environment env, Filename filename, String raw) {
@@ -279,7 +292,7 @@ public class JavaScript {
 
         try {
             stm.resolve(target);
-            stm.compile(target, true);
+            stm.compile(target, true, false, BreakpointType.NONE);
             // FunctionNode.checkBreakAndCont(target, 0);
         }
         catch (SyntaxException e) {
diff --git a/src/java/me/topchetoeu/jscript/compilation/LabelContext.java b/src/java/me/topchetoeu/jscript/compilation/LabelContext.java
index 5cfb1a3..0dea994 100644
--- a/src/java/me/topchetoeu/jscript/compilation/LabelContext.java
+++ b/src/java/me/topchetoeu/jscript/compilation/LabelContext.java
@@ -2,8 +2,8 @@ package me.topchetoeu.jscript.compilation;
 
 import java.util.HashMap;
 import java.util.LinkedList;
+import java.util.function.IntFunction;
 import java.util.function.IntSupplier;
-import java.util.function.Supplier;
 
 import me.topchetoeu.jscript.common.Instruction;
 import me.topchetoeu.jscript.common.environment.Environment;
@@ -25,15 +25,15 @@ public class LabelContext {
         return map.get(name);
     }
 
-    public Supplier<Instruction> getJump(int offset) {
+    public IntFunction<Instruction> getJump() {
         var res = get();
         if (res == null) return null;
-        else return () -> Instruction.jmp(res.getAsInt() - offset);
+        else return i -> Instruction.jmp(res.getAsInt() - i);
     }
-    public Supplier<Instruction> getJump(int offset, String name) {
+    public IntFunction<Instruction> getJump(String name) {
         var res = get(name);
         if (res == null) return null;
-        else return () -> Instruction.jmp(res.getAsInt() - offset);
+        else return i -> Instruction.jmp(res.getAsInt() - i);
     }
 
     public void push(IntSupplier jumpTarget) {
diff --git a/src/java/me/topchetoeu/jscript/compilation/Parameter.java b/src/java/me/topchetoeu/jscript/compilation/Parameter.java
new file mode 100644
index 0000000..9404d5d
--- /dev/null
+++ b/src/java/me/topchetoeu/jscript/compilation/Parameter.java
@@ -0,0 +1,15 @@
+package me.topchetoeu.jscript.compilation;
+
+import me.topchetoeu.jscript.common.parsing.Location;
+
+public final class Parameter {
+    public final Location loc;
+    public final String name;
+    public final Node node;
+
+    public Parameter(Location loc, String name, Node node) {
+        this.name = name;
+        this.node = node;
+        this.loc = loc;
+    }
+}
\ No newline at end of file
diff --git a/src/java/me/topchetoeu/jscript/compilation/Parameters.java b/src/java/me/topchetoeu/jscript/compilation/Parameters.java
new file mode 100644
index 0000000..c104a38
--- /dev/null
+++ b/src/java/me/topchetoeu/jscript/compilation/Parameters.java
@@ -0,0 +1,28 @@
+package me.topchetoeu.jscript.compilation;
+
+import java.util.HashSet;
+import java.util.List;
+import java.util.Set;
+
+public final class Parameters {
+    public final int length;
+    public final List<Parameter> params;
+    public final Set<String> names;
+
+    public Parameters(List<Parameter> params) {
+        this.names = new HashSet<>();
+        var len = params.size();
+
+        for (var i = params.size() - 1; i >= 0; i--) {
+            if (params.get(i).node == null) break;
+            len--;
+        }
+
+        for (var param : params) {
+            this.names.add(param.name);
+        }
+
+        this.params = params;
+        this.length = len;
+    }
+}
diff --git a/src/java/me/topchetoeu/jscript/compilation/VariableDeclareNode.java b/src/java/me/topchetoeu/jscript/compilation/VariableDeclareNode.java
index 84c7014..69b91f8 100644
--- a/src/java/me/topchetoeu/jscript/compilation/VariableDeclareNode.java
+++ b/src/java/me/topchetoeu/jscript/compilation/VariableDeclareNode.java
@@ -40,7 +40,7 @@ public class VariableDeclareNode extends Node {
                 target.add(VariableNode.toSet(target, entry.location, entry.name, false, true));
             }
             else {
-                target.add(() -> {
+                target.add(_i -> {
                     var i = target.scope.get(entry.name, true);
 
                     if (i == null) return Instruction.globDef(entry.name);
diff --git a/src/java/me/topchetoeu/jscript/compilation/control/BreakNode.java b/src/java/me/topchetoeu/jscript/compilation/control/BreakNode.java
index e052b30..b74e2a4 100644
--- a/src/java/me/topchetoeu/jscript/compilation/control/BreakNode.java
+++ b/src/java/me/topchetoeu/jscript/compilation/control/BreakNode.java
@@ -15,7 +15,7 @@ public class BreakNode extends Node {
     public final String label;
 
     @Override public void compile(CompileResult target, boolean pollute) {
-        var res = LabelContext.getBreak(target.env).getJump(target.size());
+        var res = LabelContext.getBreak(target.env).getJump();
         if (res == null) {
             if (label != null) throw new SyntaxException(loc(), String.format("Undefined label '%s'", label));
             else throw new SyntaxException(loc(), "Illegal break statement");
diff --git a/src/java/me/topchetoeu/jscript/compilation/control/ContinueNode.java b/src/java/me/topchetoeu/jscript/compilation/control/ContinueNode.java
index be09e72..afc94a5 100644
--- a/src/java/me/topchetoeu/jscript/compilation/control/ContinueNode.java
+++ b/src/java/me/topchetoeu/jscript/compilation/control/ContinueNode.java
@@ -15,7 +15,7 @@ public class ContinueNode extends Node {
     public final String label;
 
     @Override public void compile(CompileResult target, boolean pollute) {
-        var res = LabelContext.getCont(target.env).getJump(target.size());
+        var res = LabelContext.getCont(target.env).getJump();
         if (res == null) {
             if (label != null) throw new SyntaxException(loc(), String.format("Undefined label '%s'", label));
             else throw new SyntaxException(loc(), "Illegal continue statement");
diff --git a/src/java/me/topchetoeu/jscript/compilation/control/SwitchNode.java b/src/java/me/topchetoeu/jscript/compilation/control/SwitchNode.java
index 311a1a9..f41a997 100644
--- a/src/java/me/topchetoeu/jscript/compilation/control/SwitchNode.java
+++ b/src/java/me/topchetoeu/jscript/compilation/control/SwitchNode.java
@@ -44,7 +44,7 @@ public class SwitchNode extends Node {
         value.compile(target, true, BreakpointType.STEP_OVER);
 
         var subtarget = target.subtarget();
-        subtarget.add(() -> Instruction.stackAlloc(subtarget.scope.allocCount()));
+        subtarget.add(_i -> Instruction.stackAlloc(subtarget.scope.allocCount()));
 
         // TODO: create a jump map
         for (var ccase : cases) {
diff --git a/src/java/me/topchetoeu/jscript/compilation/scope/FunctionScope.java b/src/java/me/topchetoeu/jscript/compilation/scope/FunctionScope.java
index 5741a63..3e70aa5 100644
--- a/src/java/me/topchetoeu/jscript/compilation/scope/FunctionScope.java
+++ b/src/java/me/topchetoeu/jscript/compilation/scope/FunctionScope.java
@@ -27,7 +27,7 @@ public class FunctionScope extends Scope {
         else if (parent == null) throw new RuntimeException("Strict variables may be defined only in local scopes");
         else return parent.defineStrict(name, readonly, loc);
     }
-    public VariableDescriptor defineArg(String name, Location loc) {
+    public VariableDescriptor defineParam(String name, Location loc) {
         return specials.add(name, false);
     }
     public boolean hasArg(String name) {
diff --git a/src/java/me/topchetoeu/jscript/compilation/values/ObjectNode.java b/src/java/me/topchetoeu/jscript/compilation/values/ObjectNode.java
index 48bab87..9382b81 100644
--- a/src/java/me/topchetoeu/jscript/compilation/values/ObjectNode.java
+++ b/src/java/me/topchetoeu/jscript/compilation/values/ObjectNode.java
@@ -97,7 +97,7 @@ public class ObjectNode extends Node {
         if (!name.isSuccess()) return name.chainError(src.loc(i + n), "Expected a property name after '" + access + "'");
         n += name.n;
 
-        var params = JavaScript.parseParamList(src, i + n);
+        var params = JavaScript.parseParameters(src, i + n);
         if (!params.isSuccess()) return params.chainError(src.loc(i + n), "Expected an argument list");
         n += params.n;
 
@@ -109,7 +109,7 @@ public class ObjectNode extends Node {
 
         return ParseRes.res(new ObjProp(
             name.result, access.result,
-            new FunctionValueNode(loc, end, params.result.toArray(String[]::new), body.result, access + " " + name.result.toString())
+            new FunctionValueNode(loc, end, params.result, body.result, access + " " + name.result.toString())
         ), n);
     }
 
diff --git a/src/java/me/topchetoeu/jscript/compilation/values/VariableNode.java b/src/java/me/topchetoeu/jscript/compilation/values/VariableNode.java
index bea5355..1ced342 100644
--- a/src/java/me/topchetoeu/jscript/compilation/values/VariableNode.java
+++ b/src/java/me/topchetoeu/jscript/compilation/values/VariableNode.java
@@ -1,5 +1,6 @@
 package me.topchetoeu.jscript.compilation.values;
 
+import java.util.function.IntFunction;
 import java.util.function.Supplier;
 
 import me.topchetoeu.jscript.common.Instruction;
@@ -33,7 +34,7 @@ public class VariableNode extends Node implements AssignableNode {
         var i = target.scope.get(name, true);
 
         if (i == null) {
-            target.add((Supplier<Instruction>)() -> {
+            target.add(_i -> {
                 if (target.scope.has(name)) throw new SyntaxException(loc(), String.format("Cannot access '%s' before initialization", name));
                 return Instruction.globGet(name);
             });
@@ -45,28 +46,28 @@ public class VariableNode extends Node implements AssignableNode {
         }
     }
 
-    public static Supplier<Instruction> toGet(CompileResult target, Location loc, String name, Supplier<Instruction> onGlobal) {
+    public static IntFunction<Instruction> toGet(CompileResult target, Location loc, String name, Supplier<Instruction> onGlobal) {
         var i = target.scope.get(name, true);
 
-        if (i == null) return () -> {
+        if (i == null) return _i -> {
             if (target.scope.has(name)) throw new SyntaxException(loc, String.format("Cannot access '%s' before initialization", name));
             else return onGlobal.get();
         };
-        else return () -> Instruction.loadVar(i.index());
+        else return _i -> Instruction.loadVar(i.index());
     }
-    public static Supplier<Instruction> toGet(CompileResult target, Location loc, String name) {
+    public static IntFunction<Instruction> toGet(CompileResult target, Location loc, String name) {
         return toGet(target, loc, name, () -> Instruction.globGet(name));
     }
 
 
-    public static Supplier<Instruction> toSet(CompileResult target, Location loc, String name, boolean keep, boolean define) {
+    public static IntFunction<Instruction> toSet(CompileResult target, Location loc, String name, boolean keep, boolean define) {
         var i = target.scope.get(name, true);
 
-        if (i == null) return () -> {
+        if (i == null) return _i -> {
             if (target.scope.has(name)) throw new SyntaxException(loc, String.format("Cannot access '%s' before initialization", name));
             else return Instruction.globSet(name, keep, define);
         };
-        else return () -> Instruction.storeVar(i.index(), keep);
+        else return _i -> Instruction.storeVar(i.index(), keep);
 
     }
 
diff --git a/src/java/me/topchetoeu/jscript/runtime/Frame.java b/src/java/me/topchetoeu/jscript/runtime/Frame.java
index c979933..f91ba76 100644
--- a/src/java/me/topchetoeu/jscript/runtime/Frame.java
+++ b/src/java/me/topchetoeu/jscript/runtime/Frame.java
@@ -420,11 +420,16 @@ public final class Frame {
         this.argsVal = new ArgumentsValue(this, args);
         this.captures = func.captures;
 
-        for (var i = 0; i < func.body.argsN; i++) {
+        var i = 0;
+
+        for (; i < func.body.argsN && i < args.length; i++) {
             this.locals.add(new Value[] { args[i] });
         }
+        for (; i < args.length; i++) {
+            this.locals.add(new Value[] { Value.UNDEFINED });
+        }
 
-        for (var i = 0; i < func.body.localsN; i++) {
+        for (i = 0; i < func.body.localsN; i++) {
             this.locals.add(new Value[] { Value.UNDEFINED });
         }
 
diff --git a/src/java/me/topchetoeu/jscript/runtime/values/functions/CodeFunction.java b/src/java/me/topchetoeu/jscript/runtime/values/functions/CodeFunction.java
index 335dcdf..6eb5aa6 100644
--- a/src/java/me/topchetoeu/jscript/runtime/values/functions/CodeFunction.java
+++ b/src/java/me/topchetoeu/jscript/runtime/values/functions/CodeFunction.java
@@ -30,7 +30,7 @@ public final class CodeFunction extends FunctionValue {
     }
 
     public CodeFunction(Environment env, String name, FunctionBody body, Value[][] captures) {
-        super(name, body.argsN);
+        super(name, body.length);
         this.captures = captures;
         this.env = env;
         this.body = body;