diff --git a/modules/globals.js b/modules/globals.js
index 5d4903e4b..a2d710341 100644
--- a/modules/globals.js
+++ b/modules/globals.js
@@ -85,7 +85,7 @@ Object.defineProperty(this, "global", { value: this });
     this.setTimeout = function(callback, delay) {
         var args = Array.slice(arguments, 2);
         delay = parseInt(delay, 10) || 0;
-        var worker = engine.getCurrentWorker();
+        var worker = engine.getCurrentWorker(callback);
         return worker.schedule(delay, this, callback, args);
     };
 
@@ -121,7 +121,7 @@ Object.defineProperty(this, "global", { value: this });
     global.setInterval =  function(callback, delay) {
         var args = Array.slice(arguments, 2);
         delay = Math.max(parseInt(delay, 10) || 0, 1);
-        var worker = engine.getCurrentWorker();
+        var worker = engine.getCurrentWorker(callback);
         return worker.scheduleInterval(delay, this, callback, args);
     };
 
diff --git a/modules/ringo/engine.js b/modules/ringo/engine.js
index 9ecff0d3a..329067b17 100644
--- a/modules/ringo/engine.js
+++ b/modules/ringo/engine.js
@@ -164,11 +164,12 @@ function getWorker() {
 }
 
 /**
- * Get the current worker instance.
- * @return {org.ringojs.engine.RingoWorker} the current RingoWorker instance
+ * Get the worker instance associated with the current thread or the given scope or function object.
+ * @param obj {Object} optional scope or function to get the worker from.
+ * @return {org.ringojs.engine.RingoWorker} the current worker
  */
-function getCurrentWorker() {
-    return engine.getCurrentWorker();
+function getCurrentWorker(obj) {
+    return engine.getCurrentWorker(obj || null);
 }
 
 /**
diff --git a/src/org/ringojs/engine/Callback.java b/src/org/ringojs/engine/Callback.java
index 71fa895de..2099b45e3 100644
--- a/src/org/ringojs/engine/Callback.java
+++ b/src/org/ringojs/engine/Callback.java
@@ -51,10 +51,7 @@ public Callback(Scriptable function, RhinoEngine engine, boolean sync) {
         if (function instanceof Function) {
             this.module = scope;
             this.function = function;
-            worker = engine.getCurrentWorker();
-            if (worker == null) {
-                worker = engine.getWorker();
-            }
+            this.worker = engine.getCurrentWorker(function);
         } else {
             this.module = ScriptableObject.getProperty(function, "module");
             this.function = ScriptableObject.getProperty(function, "name");
diff --git a/src/org/ringojs/engine/ModuleScope.java b/src/org/ringojs/engine/ModuleScope.java
index 6fdfe58d8..c7a6aa67e 100644
--- a/src/org/ringojs/engine/ModuleScope.java
+++ b/src/org/ringojs/engine/ModuleScope.java
@@ -29,6 +29,7 @@ public class ModuleScope extends ImporterTopLevel {
     private Trackable source;
     private Repository repository;
     private String id;
+    private RingoWorker worker;
     private long checksum;
     private Scriptable exportsObject, moduleObject;
     private static final long serialVersionUID = -2409425841990094897L;
@@ -50,6 +51,7 @@ public ModuleScope(String moduleId, Trackable source,
         this.repository = source instanceof Repository ?
                 (Repository) source : source.getParentRepository();
         this.id = moduleId;
+        this.worker = worker;
         // create and define module meta-object
         moduleObject = new ModuleObject(this);
         defineProperty("module", moduleObject, DONTENUM);
@@ -69,6 +71,10 @@ public Repository getRepository() {
         return repository;
     }
 
+    public RingoWorker getWorker() {
+        return worker;
+    }
+
     public void reset() {
         Scriptable exports = new ExportsObject();
         defineProperty("exports", exports,  DONTENUM);
diff --git a/src/org/ringojs/engine/Require.java b/src/org/ringojs/engine/Require.java
index 543e38372..08d42368f 100644
--- a/src/org/ringojs/engine/Require.java
+++ b/src/org/ringojs/engine/Require.java
@@ -76,10 +76,7 @@ public Object call(Context cx, Scriptable scope, Scriptable thisObj, Object[] ar
         ModuleScope moduleScope = thisObj instanceof ModuleScope ?
                 (ModuleScope) thisObj : null;
         try {
-            RingoWorker worker = engine.getCurrentWorker();
-            if (worker == null) {
-                worker = engine.getMainWorker();
-            }
+            RingoWorker worker = engine.getCurrentWorker(scope);
             String arg = args[0].toString();
             Scriptable module = worker.loadModule(cx, arg, moduleScope);
             return module instanceof ModuleScope ?
diff --git a/src/org/ringojs/engine/RhinoEngine.java b/src/org/ringojs/engine/RhinoEngine.java
index f046e14bc..1abd9b43a 100644
--- a/src/org/ringojs/engine/RhinoEngine.java
+++ b/src/org/ringojs/engine/RhinoEngine.java
@@ -275,11 +275,35 @@ protected RingoWorker setCurrentWorker(RingoWorker worker) {
     }
 
     /**
-     * Get the worker associated with the given scope, or null.
-     * @return the worker associated with the current thread, or null.
+     * Get the worker associated with the current thread, or the given scope or function argument if provided.
+     * An {@code IllegalStateException} is thrown if no worker could be found or if different workers are
+     * associated with the current thread and the argument object.
+     *
+     * @param obj a scope or function object
+     * @throws IllegalStateException if no worker could be found, or if different workers are associates with
+     * the current thread and the argument object
+     * @return the current worker
      */
-    public RingoWorker getCurrentWorker() {
-        return currentWorker.get();
+    public RingoWorker getCurrentWorker(Scriptable obj) {
+        RingoWorker worker = currentWorker.get();  // Get worker associated with current thread
+        Scriptable scriptable = obj;
+
+        while (scriptable != null) {
+            if (scriptable instanceof ModuleScope) {
+                RingoWorker scopeWorker = ((ModuleScope) scriptable).getWorker();
+                if (worker == null) {
+                    worker = scopeWorker;
+                } else if (worker != scopeWorker) {
+                    throw new IllegalStateException("Current thread worker differs from scope worker");
+                }
+                break;
+            }
+            scriptable = scriptable.getParentScope();
+        }
+        if (worker == null) {
+            throw new IllegalStateException("No worker associated with current thread or scope");
+        }
+        return worker;
     }
 
     /**