diff --git a/plugins/GSdx/res/tfx.fx b/plugins/GSdx/res/tfx.fx
index cdd9ec4c47..7d56b29866 100644
--- a/plugins/GSdx/res/tfx.fx
+++ b/plugins/GSdx/res/tfx.fx
@@ -506,7 +506,7 @@ void datst(PS_INPUT input)
 
 void atst(float4 c)
 {
-	float a = trunc(c.a * 255);
+	float a = trunc(c.a * 255 + 0.01);
 	
 	if(PS_ATST == 0) // never
 	{