diff --git a/src/me/topchetoeu/jscript/Main.java b/src/me/topchetoeu/jscript/Main.java
index 4180c06..fe9625e 100644
--- a/src/me/topchetoeu/jscript/Main.java
+++ b/src/me/topchetoeu/jscript/Main.java
@@ -102,7 +102,7 @@ public class Main {
                         var raw = in.readLine();
 
                         if (raw == null) break;
-                        engine.pushMsg(false, new Context(env, new Message(engine)), "<stdio>", raw, null).toObservable().once(valuePrinter);
+                        engine.pushMsg(false, env.context(new Message(engine)), "<stdio>", raw, null).toObservable().once(valuePrinter);
                     }
                     catch (EngineException e) {
                         try {
diff --git a/src/me/topchetoeu/jscript/engine/Data.java b/src/me/topchetoeu/jscript/engine/Data.java
new file mode 100644
index 0000000..49d18b7
--- /dev/null
+++ b/src/me/topchetoeu/jscript/engine/Data.java
@@ -0,0 +1,58 @@
+package me.topchetoeu.jscript.engine;
+
+import java.util.HashMap;
+import java.util.Iterator;
+import java.util.Map.Entry;
+
+@SuppressWarnings("unchecked")
+public class Data implements Iterable<Entry<DataKey<?>, ?>> {
+    private HashMap<DataKey<Object>, Object> data = new HashMap<>();
+
+    public Data copy() {
+        return new Data().addAll(this);
+    }
+
+    public Data addAll(Iterable<Entry<DataKey<?>, ?>> data) {
+        for (var el : data) {
+            add((DataKey<Object>)el.getKey(), (Object)el.getValue());
+        }
+        return this;
+    }
+
+    public <T> Data set(DataKey<T> key, T val) {
+        if (val == null) data.remove(key);
+        else data.put((DataKey<Object>)key, (Object)val);
+        return this;
+    }
+    public <T> T add(DataKey<T> key, T val) {
+        if (data.containsKey(key)) return (T)data.get(key);
+        else {
+            if (val == null) data.remove(key);
+            else data.put((DataKey<Object>)key, (Object)val);
+            return val;
+        }
+    }
+    public <T> T get(DataKey<T> key) {
+        return get(key, null);
+    }
+    public <T> T get(DataKey<T> key, T defaultVal) {
+        if (!has(key)) return defaultVal;
+        else return (T)data.get(key);
+    }
+    public boolean has(DataKey<?> key) { return data.containsKey(key); }
+
+    public Data increase(DataKey<Integer> key, int n, int start) {
+        return set(key, get(key, start) + n);
+    }
+    public Data increase(DataKey<Integer> key, int n) {
+        return increase(key, n, 0);
+    }
+    public Data increase(DataKey<Integer> key) {
+        return increase(key, 1, 0);
+    }
+
+    @Override
+    public Iterator<Entry<DataKey<?>, ?>> iterator() {
+        return (Iterator<Entry<DataKey<?>, ?>>)data.entrySet();
+    }
+}
diff --git a/src/me/topchetoeu/jscript/engine/DataKey.java b/src/me/topchetoeu/jscript/engine/DataKey.java
new file mode 100644
index 0000000..017fa2a
--- /dev/null
+++ b/src/me/topchetoeu/jscript/engine/DataKey.java
@@ -0,0 +1,3 @@
+package me.topchetoeu.jscript.engine;
+
+public class DataKey<T> { }
\ No newline at end of file
diff --git a/src/me/topchetoeu/jscript/engine/Engine.java b/src/me/topchetoeu/jscript/engine/Engine.java
index aa83065..013b66e 100644
--- a/src/me/topchetoeu/jscript/engine/Engine.java
+++ b/src/me/topchetoeu/jscript/engine/Engine.java
@@ -11,19 +11,19 @@ public class Engine {
     private class UncompiledFunction extends FunctionValue {
         public final String filename;
         public final String raw;
-        public final Environment ctx;
+        public final Environment env;
 
         @Override
         public Object call(Context ctx, Object thisArg, Object ...args) throws InterruptedException {
-            ctx = new Context(this.ctx, ctx.message);
+            ctx = ctx.setEnv(env);
             return ctx.compile(filename, raw).call(ctx, thisArg, args);
         }
 
-        public UncompiledFunction(Environment ctx, String filename, String raw) {
+        public UncompiledFunction(Environment env, String filename, String raw) {
             super(filename, 0);
             this.filename = filename;
             this.raw = raw;
-            this.ctx = ctx; 
+            this.env = env; 
         }
     }
 
@@ -32,10 +32,10 @@ public class Engine {
         public final Object thisArg;
         public final Object[] args;
         public final DataNotifier<Object> notifier = new DataNotifier<>();
-        public final Message ctx;
+        public final Message msg;
 
         public Task(Message ctx, FunctionValue func, Object thisArg, Object[] args) {
-            this.ctx = ctx;
+            this.msg = ctx;
             this.func = func;
             this.thisArg = thisArg;
             this.args = args;
@@ -52,7 +52,7 @@ public class Engine {
 
     private void runTask(Task task) throws InterruptedException {
         try {
-            task.notifier.next(task.func.call(new Context(null, task.ctx), task.thisArg, task.args));
+            task.notifier.next(task.func.call(task.msg.context(null), task.thisArg, task.args));
         }
         catch (InterruptedException e) {
             task.notifier.error(new RuntimeException(e));
diff --git a/src/me/topchetoeu/jscript/engine/Environment.java b/src/me/topchetoeu/jscript/engine/Environment.java
index 5821c04..c8136cf 100644
--- a/src/me/topchetoeu/jscript/engine/Environment.java
+++ b/src/me/topchetoeu/jscript/engine/Environment.java
@@ -15,15 +15,23 @@ import me.topchetoeu.jscript.interop.NativeWrapperProvider;
 
 public class Environment {
     private HashMap<String, ObjectValue> prototypes = new HashMap<>();
+
+    public final Data data = new Data();
+    public final HashMap<String, Symbol> symbols = new HashMap<>();
+
     public GlobalScope global;
     public WrappersProvider wrappersProvider;
-    /** NOTE: This is not the register for Symbol.for, but for the symbols like Symbol.iterator */
-    public HashMap<String, Symbol> symbols = new HashMap<>();
 
     @Native public FunctionValue compile;
     @Native public FunctionValue regexConstructor = new NativeFunction("RegExp", (ctx, thisArg, args) -> {
         throw EngineException.ofError("Regular expressions not supported.").setContext(ctx);
     });
+
+    public Environment addData(Data data) {
+        this.data.addAll(data);
+        return this;
+    }
+
     @Native public ObjectValue proto(String name) {
         return prototypes.get(name);
     }
diff --git a/src/me/topchetoeu/jscript/engine/Message.java b/src/me/topchetoeu/jscript/engine/Message.java
index 974893f..b61f522 100644
--- a/src/me/topchetoeu/jscript/engine/Message.java
+++ b/src/me/topchetoeu/jscript/engine/Message.java
@@ -13,8 +13,15 @@ public class Message {
     private final ArrayList<CodeFrame> frames = new ArrayList<>();
     public int maxStackFrames = 1000;
 
+    public final Data data = new Data();
+
     public List<CodeFrame> frames() { return Collections.unmodifiableList(frames); }
 
+    public Message addData(Data data) {
+        this.data.addAll(data);
+        return this;
+    }
+
     public Message pushFrame(Context ctx, CodeFrame frame) throws InterruptedException {
         this.frames.add(frame);
         if (this.frames.size() > maxStackFrames) throw EngineException.ofRange("Stack overflow!");
diff --git a/src/me/topchetoeu/jscript/engine/values/CodeFunction.java b/src/me/topchetoeu/jscript/engine/values/CodeFunction.java
index 0b34425..c0025b3 100644
--- a/src/me/topchetoeu/jscript/engine/values/CodeFunction.java
+++ b/src/me/topchetoeu/jscript/engine/values/CodeFunction.java
@@ -29,7 +29,7 @@ public class CodeFunction extends FunctionValue {
 
     @Override
     public Object call(Context ctx, Object thisArg, Object ...args) throws InterruptedException {
-        return new CodeFrame(ctx, thisArg, args, this).run(new Context(environment, ctx.message));
+        return new CodeFrame(ctx, thisArg, args, this).run(ctx.setEnv(environment));
     }
 
     public CodeFunction(Environment environment, String name, int localsN, int length, ValueVariable[] captures, Instruction[] body) {