diff --git a/src/qt/qt_softwarerenderer.cpp b/src/qt/qt_softwarerenderer.cpp
index 49f683bc0..bb6c7508b 100644
--- a/src/qt/qt_softwarerenderer.cpp
+++ b/src/qt/qt_softwarerenderer.cpp
@@ -64,7 +64,7 @@ SoftwareRenderer::onBlit(int buf_idx, int x, int y, int w, int h)
     auto origSource = source;
 
     cur_image = buf_idx;
-    buf_usage[(buf_idx + 1) % 2].clear();
+    buf_usage[buf_idx ^ 1].clear();
 
     source.setRect(x, y, w, h);