--- a/js/jsd/jsd_xpc.cpp
+++ b/js/jsd/jsd_xpc.cpp
@@ -518,18 +518,24 @@ jsds_GCCallbackProc (JSContext *cx, JSGC
     if (status == JSGC_END) {
         /* just to guard against reentering. */
         gGCStatus = JSGC_BEGIN;
         while (gDeadScripts)
             jsds_NotifyPendingDeadScripts (cx);
     }
 
     gGCStatus = status;
-    if (gLastGCProc)
-        return gLastGCProc (cx, status);
+    if (gLastGCProc && !gLastGCProc (cx, status)) {
+        /*
+         * If gLastGCProc returns false, then we're going to abort out
+         * of this GC pass without a JSGC_END callback.
+         */
+        gGCStatus = JSGC_END;
+        return JS_FALSE;
+    }
     
     return JS_TRUE;
 }
 
 static uintN
 jsds_ErrorHookProc (JSDContext *jsdc, JSContext *cx, const char *message,
                     JSErrorReport *report, void *callerdata)
 {
@@ -2590,17 +2596,18 @@ jsdService::Off (void)
     if (!mCx || !mRuntime)
         return NS_ERROR_NOT_INITIALIZED;
     
     if (gDeadScripts) {
         if (gGCStatus != JSGC_END)
             return NS_ERROR_NOT_AVAILABLE;
 
         JSContext *cx = JSD_GetDefaultJSContext(mCx);
-        jsds_NotifyPendingDeadScripts(cx);
+        while (gDeadScripts)
+            jsds_NotifyPendingDeadScripts (cx);
     }
 
     /*
     if (gLastGCProc != jsds_GCCallbackProc)
         JS_SetGCCallbackRT (mRuntime, gLastGCProc);
     */
 
     jsdContext::InvalidateAll();