diff --git a/js/jsd/jsd.h b/js/jsd/jsd.h
index 28101976bb9d..e98279ea908f 100644
--- a/js/jsd/jsd.h
+++ b/js/jsd/jsd.h
@@ -389,6 +389,12 @@ extern JSDScript*
 jsd_FindJSDScript(JSDContext*  jsdc,
                   JSScript     *script);
 
+extern JSDScript*
+jsd_FindOrCreateJSDScript(JSDContext    *jsdc,
+                          JSContext     *cx,
+                          JSScript      *script,
+                          JSStackFrame  *fp);
+
 extern JSDProfileData*
 jsd_GetScriptProfileData(JSDContext* jsdc, JSDScript *script);
 
diff --git a/js/jsd/jsd_hook.c b/js/jsd/jsd_hook.c
index 5ee6c9d56066..45c6be8e5979 100644
--- a/js/jsd/jsd_hook.c
+++ b/js/jsd/jsd_hook.c
@@ -66,7 +66,7 @@ jsd_InterruptHandler(JSContext *cx, JSScript *script, jsbytecode *pc, jsval *rva
         return JSTRAP_CONTINUE;
     
     JSD_LOCK_SCRIPTS(jsdc);
-    jsdscript = jsd_FindJSDScript(jsdc, script);
+    jsdscript = jsd_FindOrCreateJSDScript(jsdc, cx, script, NULL);
     JSD_UNLOCK_SCRIPTS(jsdc);
     if( ! jsdscript )
         return JSTRAP_CONTINUE;
@@ -104,7 +104,7 @@ jsd_DebuggerHandler(JSContext *cx, JSScript *script, jsbytecode *pc,
         return JSTRAP_CONTINUE;
 
     JSD_LOCK_SCRIPTS(jsdc);
-    jsdscript = jsd_FindJSDScript(jsdc, script);
+    jsdscript = jsd_FindOrCreateJSDScript(jsdc, cx, script, NULL);
     JSD_UNLOCK_SCRIPTS(jsdc);
     if( ! jsdscript )
         return JSTRAP_CONTINUE;
@@ -138,7 +138,7 @@ jsd_ThrowHandler(JSContext *cx, JSScript *script, jsbytecode *pc,
         return JSD_HOOK_RETURN_CONTINUE_THROW;
 
     JSD_LOCK_SCRIPTS(jsdc);
-    jsdscript = jsd_FindJSDScript(jsdc, script);
+    jsdscript = jsd_FindOrCreateJSDScript(jsdc, cx, script, NULL);
     JSD_UNLOCK_SCRIPTS(jsdc);
     if( ! jsdscript )
         return JSD_HOOK_RETURN_CONTINUE_THROW;
diff --git a/js/jsd/jsd_obj.c b/js/jsd/jsd_obj.c
index 89283c7468f1..c5eee186703a 100644
--- a/js/jsd/jsd_obj.c
+++ b/js/jsd/jsd_obj.c
@@ -205,7 +205,7 @@ jsd_Constructing(JSDContext* jsdc, JSContext *cx, JSObject *obj,
                 jsdobj->ctorURL = jsd_AddAtom(jsdc, ctorURL);
 
             JSD_LOCK_SCRIPTS(jsdc);
-            jsdscript = jsd_FindJSDScript(jsdc, script);
+            jsdscript = jsd_FindOrCreateJSDScript(jsdc, cx, script, fp);
             JSD_UNLOCK_SCRIPTS(jsdc);
             if( jsdscript )
             {
diff --git a/js/jsd/jsd_scpt.c b/js/jsd/jsd_scpt.c
index 1baf98dbaf09..581c0efdcce2 100644
--- a/js/jsd/jsd_scpt.c
+++ b/js/jsd/jsd_scpt.c
@@ -284,7 +284,29 @@ jsd_FindJSDScript( JSDContext*  jsdc,
 {
     JS_ASSERT(JSD_SCRIPTS_LOCKED(jsdc));
     return (JSDScript*) JS_HashTableLookup(jsdc->scriptsTable, (void *)script);
-}               
+}
+
+JSDScript *
+jsd_FindOrCreateJSDScript(JSDContext    *jsdc,
+                          JSContext     *cx,
+                          JSScript      *script,
+                          JSStackFrame  *fp)
+{
+    JSDScript *jsdscript;
+    JS_ASSERT(JSD_SCRIPTS_LOCKED(jsdc));
+
+    jsdscript = jsd_FindJSDScript(jsdc, script);
+    if (jsdscript)
+        return jsdscript;
+
+    // Fallback for unknown scripts: create a new script
+    if (!fp)
+        JS_FrameIterator(cx, &fp);
+    if (fp)
+        jsdscript = _newJSDScript(jsdc, cx, script, JS_GetFrameFunction(cx, fp));
+
+    return jsdscript;
+}
 
 JSDProfileData*
 jsd_GetScriptProfileData(JSDContext* jsdc, JSDScript *script)
diff --git a/js/jsd/jsd_step.c b/js/jsd/jsd_step.c
index 2904ffbb01bc..88a1bce3942c 100644
--- a/js/jsd/jsd_step.c
+++ b/js/jsd/jsd_step.c
@@ -76,7 +76,7 @@ _interpreterTrace(JSDContext* jsdc, JSContext *cx, JSStackFrame *fp,
     if(script)
     {
         JSD_LOCK_SCRIPTS(jsdc);
-        jsdscript = jsd_FindJSDScript(jsdc, script);
+        jsdscript = jsd_FindOrCreateJSDScript(jsdc, cx, script, fp);
         JSD_UNLOCK_SCRIPTS(jsdc);
         if(jsdscript)
             funName = JSD_GetScriptFunctionName(jsdc, jsdscript);
@@ -136,7 +136,7 @@ _callHook(JSDContext *jsdc, JSContext *cx, JSStackFrame *fp, JSBool before,
     if (jsscript)
     {
         JSD_LOCK_SCRIPTS(jsdc);
-        jsdscript = jsd_FindJSDScript(jsdc, jsscript);
+        jsdscript = jsd_FindOrCreateJSDScript(jsdc, cx, jsscript, fp);
         JSD_UNLOCK_SCRIPTS(jsdc);
     
         if (jsdscript)