--- a/widget/gtk/WindowSurfaceProvider.cpp
+++ b/widget/gtk/WindowSurfaceProvider.cpp
@@ -89,17 +89,17 @@ WindowSurfaceProvider::StartRemoteDrawin
     mWindowSurface = CreateWindowSurface();
     if (!mWindowSurface)
       return nullptr;
   }
 
   *aBufferMode = BufferMode::BUFFER_NONE;
   RefPtr<DrawTarget> dt = nullptr;
   if (!(dt = mWindowSurface->Lock(aInvalidRegion))) {
-    gfxWarningOnce() << "Failed to lock WindowSurface, falling back to XPutImage backend.";
+      gfxWarningOnce() << "Failed to lock WindowSurface, falling back to XPutImage backend: Mask (" << gfx::hexa(mXVisual->red_mask) << ", " << gfx::hexa(mXVisual->green_mask) << ", " << gfx::hexa(mXVisual->blue_mask) << "), depth: " << mXDepth;
     mWindowSurface = MakeUnique<WindowSurfaceX11Image>(mXDisplay, mXWindow, mXVisual, mXDepth);
   }
   return dt.forget();
 }
 
 void
 WindowSurfaceProvider::EndRemoteDrawingInRegion(gfx::DrawTarget* aDrawTarget,
                                               LayoutDeviceIntRegion& aInvalidRegion)