--- a/shell/avmshell.cpp
+++ b/shell/avmshell.cpp
@@ -109,25 +109,27 @@ namespace avmshell
             if (instance->settings.do_log)
               initializeLogging(instance->settings.numfiles > 0 ? instance->settings.filenames[0] : "AVMLOG");
 
 #ifdef VMCFG_WORKERTHREADS
             if (instance->settings.numworkers == 1 && instance->settings.numthreads == 1 && instance->settings.repeats == 1) 
             {
                 avmplus::Isolate* isolate = instance->newIsolate(NULL); 
                 instance->stateTransition(isolate, avmplus::Isolate::CANSTART);
+				isolate->IncrementRef();
                 isolate->run();
             }
             else
             {
                 instance->multiWorker(instance->settings);
             }
 #else
             avmplus::Isolate* isolate = instance->newIsolate(NULL); 
             instance->stateTransition(isolate, avmplus::Isolate::CANSTART);
+			isolate->IncrementRef();
 			isolate->run();
 #endif
             instance->waitUntilNoIsolates();
             // Shell is refcounted now
             //mmfx_delete(instance);
         }
 
         MMgc::GCHeap::Destroy();