diff --git a/layout/style/nsStyleStruct.h b/layout/style/nsStyleStruct.h
index b7711f75a7..b29adafcbe 100644
--- a/layout/style/nsStyleStruct.h
+++ b/layout/style/nsStyleStruct.h
@@ -1259,13 +1259,13 @@ struct MOZ_NEEDS_MEMMOVABLE_MEMBERS nsStyleBorder
 
   uint8_t GetBorderStyle(mozilla::Side aSide) const
   {
-    NS_ASSERTION(aSide <= eSideLeft, "bad side");
+    NS_ASSERTION(aSide <= mozilla::eSideLeft, "bad side");
     return mBorderStyle[aSide];
   }
 
   void SetBorderStyle(mozilla::Side aSide, uint8_t aStyle)
   {
-    NS_ASSERTION(aSide <= eSideLeft, "bad side");
+    NS_ASSERTION(aSide <= mozilla::eSideLeft, "bad side");
     mBorderStyle[aSide] = aStyle;
     mComputedBorder.Side(aSide) =
       (HasVisibleStyle(aSide) ? mBorder.Side(aSide) : 0);