diff --git a/libs/canvas/canvas.cc b/libs/canvas/canvas.cc
index 0c0d024836..133e09484c 100644
--- a/libs/canvas/canvas.cc
+++ b/libs/canvas/canvas.cc
@@ -113,7 +113,7 @@ Canvas::render (Rect const & area, Cairo::RefPtr<Cairo::Context> const & context
 
 		_root.render (*draw, context);
 
-#ifdef CANVAS_DEBUG
+#if defined CANVAS_DEBUG && !PLATFORM_WINDOWS
 		if (getenv ("CANVAS_HARLEQUIN_DEBUGGING")) {
 			// This transparently colors the rect being rendered, after it has been drawn.
 			double r = (random() % 65536) /65536.0;