diff --git a/gfx/thebes/gfxPrefs.h b/gfx/thebes/gfxPrefs.h
index deb06e31fe5f..3a3ef4e99b05 100644
--- a/gfx/thebes/gfxPrefs.h
+++ b/gfx/thebes/gfxPrefs.h
@@ -523,6 +523,7 @@ private:
   DECL_GFX_PREF(Once, "gfx.webrender.all.qualified",           WebRenderAllQualified, bool, true);
   DECL_GFX_PREF(Live, "gfx.webrender.blob-images",             WebRenderBlobImages, bool, true);
   DECL_GFX_PREF(Live, "gfx.webrender.blob.invalidation",       WebRenderBlobInvalidation, bool, false);
+  DECL_GFX_PREF(Live, "gfx.webrender.blob.paint-flashing",     WebRenderBlobPaintFlashing, bool, false);
   DECL_GFX_PREF(Live, "gfx.webrender.dl.dump-parent",          WebRenderDLDumpParent, bool, false);
   DECL_GFX_PREF(Live, "gfx.webrender.dl.dump-content",         WebRenderDLDumpContent, bool, false);
   DECL_GFX_PREF(Once, "gfx.webrender.enabled",                 WebRenderEnabledDoNotUseDirectly, bool, false);
diff --git a/gfx/webrender_bindings/Moz2DImageRenderer.cpp b/gfx/webrender_bindings/Moz2DImageRenderer.cpp
index 53308d506ae2..44cf6785eeb0 100644
--- a/gfx/webrender_bindings/Moz2DImageRenderer.cpp
+++ b/gfx/webrender_bindings/Moz2DImageRenderer.cpp
@@ -4,6 +4,7 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
+#include "gfxPrefs.h"
 #include "gfxUtils.h"
 #include "mozilla/Mutex.h"
 #include "mozilla/Range.h"
@@ -447,13 +448,13 @@ static bool Moz2DRenderCallback(const Range<const uint8_t> aBlob,
     offset = extra_end;
   }
 
-#if 0
-  dt->SetTransform(gfx::Matrix());
-  float r = float(rand()) / RAND_MAX;
-  float g = float(rand()) / RAND_MAX;
-  float b = float(rand()) / RAND_MAX;
-  dt->FillRect(gfx::Rect(0, 0, aSize.width, aSize.height), gfx::ColorPattern(gfx::Color(r, g, b, 0.5)));
-#endif
+  if (gfxPrefs::WebRenderBlobPaintFlashing()) {
+    dt->SetTransform(gfx::Matrix());
+    float r = float(rand()) / RAND_MAX;
+    float g = float(rand()) / RAND_MAX;
+    float b = float(rand()) / RAND_MAX;
+    dt->FillRect(gfx::Rect(origin.x, origin.y, aSize.width, aSize.height), gfx::ColorPattern(gfx::Color(r, g, b, 0.5)));
+  }
 
   if (aDirtyRect) {
     dt->PopClip();
diff --git a/modules/libpref/init/all.js b/modules/libpref/init/all.js
index 0cb545d23425..0d96637a9c55 100644
--- a/modules/libpref/init/all.js
+++ b/modules/libpref/init/all.js
@@ -906,6 +906,7 @@ pref("gfx.compositor.glcontext.opaque", false);
 pref("gfx.webrender.highlight-painted-layers", false);
 pref("gfx.webrender.blob-images", true);
 pref("gfx.webrender.blob.invalidation", true);
+pref("gfx.webrender.blob.paint-flashing", false);
 
 // WebRender debugging utilities.
 pref("gfx.webrender.debug.texture-cache", false);