diff --git a/widget/Screen.cpp b/widget/Screen.cpp
index 7ed3203cfc78..33f50fdd596d 100644
--- a/widget/Screen.cpp
+++ b/widget/Screen.cpp
@@ -136,7 +136,12 @@ Screen::GetContentsScaleFactor(double *aOutScale)
 NS_IMETHODIMP
 Screen::GetDefaultCSSScaleFactor(double *aOutScale)
 {
-  *aOutScale = mDefaultCssScale.scale;
+  double scale = nsIWidget::DefaultScaleOverride();
+  if (scale > 0.0) {
+    *aOutScale = scale;
+  } else {
+    *aOutScale = mDefaultCssScale.scale;
+  }
   return NS_OK;
 }
 
diff --git a/widget/gtk/ScreenHelperGTK.cpp b/widget/gtk/ScreenHelperGTK.cpp
index 555116ee182c..405b81178551 100644
--- a/widget/gtk/ScreenHelperGTK.cpp
+++ b/widget/gtk/ScreenHelperGTK.cpp
@@ -145,17 +145,17 @@ ScreenHelperGTK::GetGTKMonitorScaleFactor()
 static float
 GetDefaultCssScale()
 {
-  double scale = nsIWidget::DefaultScaleOverride();
-  if (scale <= 0.0) {
-    scale = ScreenHelperGTK::GetGTKMonitorScaleFactor() * gfxPlatformGtk::GetDPIScale();
-  }
-  return scale;
+  return ScreenHelperGTK::GetGTKMonitorScaleFactor() * gfxPlatformGtk::GetDPIScale();
 }
 
 float
 ScreenHelperGTK::GetSystemDefaultScale()
 {
-  return GetDefaultCssScale();
+  double scale = nsIWidget::DefaultScaleOverride();
+  if (scale <= 0.0) {
+    scale = GetDefaultCssScale();
+  }
+  return scale;
 }
 
 static uint32_t
diff --git a/widget/windows/ScreenHelperWin.cpp b/widget/windows/ScreenHelperWin.cpp
index 1a28560b18f2..00c757a067a0 100644
--- a/widget/windows/ScreenHelperWin.cpp
+++ b/widget/windows/ScreenHelperWin.cpp
@@ -34,10 +34,7 @@ CollectMonitors(HMONITOR aMon, HDC, LPRECT, LPARAM ioParam)
   } else {
     contentsScaleFactor.scale = scale;
   }
-  CSSToLayoutDeviceScale defaultCssScaleFactor(nsIWidget::DefaultScaleOverride());
-  if (defaultCssScaleFactor.scale <= 0.0) {
-    defaultCssScaleFactor.scale = scale;
-  }
+  CSSToLayoutDeviceScale defaultCssScaleFactor(scale);
   LayoutDeviceIntRect rect(info.rcMonitor.left, info.rcMonitor.top,
                            info.rcMonitor.right - info.rcMonitor.left,
                            info.rcMonitor.bottom - info.rcMonitor.top);