diff --git a/src/Backends/Rendering/Software.cpp b/src/Backends/Rendering/Software.cpp
index 110a1bc5..f6237eaa 100644
--- a/src/Backends/Rendering/Software.cpp
+++ b/src/Backends/Rendering/Software.cpp
@@ -240,7 +240,7 @@ ATTRIBUTE_HOT void RenderBackend_ColourFill(RenderBackend_Surface *surface, cons
 
 	for (long j = 0; j < rect_clamped.bottom - rect_clamped.top; ++j)
 	{
-		unsigned char *destination_pointer = &surface->pixels[((rect_clamped.top + j) * surface->pitch) + (rect_clamped.left * 3)];
+		unsigned char *destination_pointer = &surface->pixels[((rect_clamped.top + j) * surface->pitch) + (rect_clamped.left * 4)];
 
 		for (long i = 0; i < rect_clamped.right - rect_clamped.left; ++i)
 		{