diff --git a/mozilla/layout/xul/base/src/nsBox.cpp b/mozilla/layout/xul/base/src/nsBox.cpp
index ea727be2652..85d9193cca4 100644
--- a/mozilla/layout/xul/base/src/nsBox.cpp
+++ b/mozilla/layout/xul/base/src/nsBox.cpp
@@ -532,7 +532,9 @@ nsBox::GetPrefSize(nsBoxLayoutState& aState)
   AddInset(pref);
   nsIBox::AddCSSPrefSize(aState, this, pref);
 
-  BoundsCheck(GetMinSize(aState), pref, GetMaxSize(aState));
+  nsSize minSize = GetMinSize(aState);
+  nsSize maxSize = GetMaxSize(aState);
+  BoundsCheck(minSize, pref, maxSize);
 
   return pref;
 }