diff --git a/desmume/src/cocoa/openemu/NDSGameCore.mm b/desmume/src/cocoa/openemu/NDSGameCore.mm
index 404b92109..4ee8935fb 100644
--- a/desmume/src/cocoa/openemu/NDSGameCore.mm
+++ b/desmume/src/cocoa/openemu/NDSGameCore.mm
@@ -176,7 +176,9 @@
 
 - (void)resetEmulation
 {
+	pthread_mutex_lock(&mutexCoreExecute);
 	NDS_Reset();
+	pthread_mutex_unlock(&mutexCoreExecute);
 	execute = true;
 }