--- a/widget/windows/nsWindow.cpp
+++ b/widget/windows/nsWindow.cpp
@@ -1091,17 +1091,17 @@ float nsWindow::GetDPI()
   return float(heightPx/heightInches);
 }
 
 double nsWindow::GetDefaultScaleInternal()
 {
   if (mDefaultScale <= 0.0) {
     mDefaultScale = WinUtils::LogToPhysFactor(mWnd);
   }
-  return WinUtils::LogToPhysFactor(mWnd);
+  return mDefaultScale;
 }
 
 int32_t nsWindow::LogToPhys(double aValue)
 {
   return WinUtils::LogToPhys(::MonitorFromWindow(mWnd,
                                                  MONITOR_DEFAULTTOPRIMARY),
                              aValue);
 }