diff --git a/src/c/threads.d b/src/c/threads.d
index cc4e63a55..a46429d92 100644
--- a/src/c/threads.d
+++ b/src/c/threads.d
@@ -405,7 +405,7 @@ mp_process_enable(cl_object process)
 	DWORD threadId;
 
 	code = (HANDLE)CreateThread(NULL, 0, thread_entry_point, process, 0, &threadId);
-	ok = (process->process.thread = code);
+	ok = (process->process.thread = code) != NULL;
 	}
 #else
 	{