diff --git a/indra/lldarwin/llwindowmacosx-objc.mm b/indra/lldarwin/llwindowmacosx-objc.mm
index 04fc52e299eb5d7204c4b0c94578c847d6085002..c0a88885f7ba48bef6c4c8d4a103bea85f90d2e9 100644
--- a/indra/lldarwin/llwindowmacosx-objc.mm
+++ b/indra/lldarwin/llwindowmacosx-objc.mm
@@ -240,7 +240,7 @@ unsigned long getVramSize(GLViewRef view)
 
 float getDeviceUnitSize(GLViewRef view)
 {
-    return ((__bridge LLOpenGLView*)view).window.backingScaleFactor;
+    return [(__bridge LLOpenGLView*)view convertSizeToBacking:NSMakeSize(1, 1)].width;
 }
 
 void getContentViewBounds(NSWindowRef window, float* bounds)