diff --git a/OSBindings/Mac/Clock Signal/CSCathodeRayView.m b/OSBindings/Mac/Clock Signal/CSCathodeRayView.m
index e3a9d4277..5537ee36c 100644
--- a/OSBindings/Mac/Clock Signal/CSCathodeRayView.m	
+++ b/OSBindings/Mac/Clock Signal/CSCathodeRayView.m	
@@ -50,7 +50,7 @@
 	CVDisplayLinkStart(displayLink);
 
 	glEnable(GL_BLEND);
-	glBlendFunc(GL_SRC_ALPHA, GL_ONE);
+	glBlendFunc(GL_SRC_ALPHA, GL_ZERO);
 }
 
 static CVReturn DisplayLinkCallback(CVDisplayLinkRef displayLink, const CVTimeStamp *now, const CVTimeStamp *outputTime, CVOptionFlags flagsIn, CVOptionFlags *flagsOut, void *displayLinkContext)