diff --git a/V8Context.cpp b/V8Context.cpp
index e685111..3e4c6ce 100644
--- a/V8Context.cpp
+++ b/V8Context.cpp
@@ -413,6 +413,7 @@ class thread_canceller {
             V8::TerminateExecution(me->isolate_);
         }
         pthread_mutex_unlock(&me->mutex_);
+        return NULL;
     }
 
     pthread_t id_;