diff --git a/GPU/GLES/StateMapping.cpp b/GPU/GLES/StateMapping.cpp
index 501c31bd33..6b9683be58 100644
--- a/GPU/GLES/StateMapping.cpp
+++ b/GPU/GLES/StateMapping.cpp
@@ -363,11 +363,7 @@ void TransformDrawEngine::ApplyDrawState(int prim) {
 		vpHeight *= renderHeightFactor;
 
 		// Flip vpY0 to match the OpenGL coordinate system.
-		vpY0 = renderHeight - (vpY0 + vpHeight);
-		
-		// Clamp vpX0/vpY0 to zero when negative value retured.
-		vpY0 = vpY0 < 0 ? 0 : vpY0;
-		vpX0 = vpX0 < 0 ? 0 : vpX0;
+		vpY0 = renderHeight - (vpYb - offsetY + fabsf(vpYa)) * renderHeightFactor;
 		
 		glstate.viewport.set(vpX0 + renderX, vpY0 + renderY, vpWidth, vpHeight);
 		// Sadly, as glViewport takes integers, we will not be able to support sub pixel offsets this way. But meh.