--- a/layout/generic/nsFrame.cpp
+++ b/layout/generic/nsFrame.cpp
@@ -1891,17 +1891,16 @@ nsIFrame::GetShapeBoxBorderRadii(nscoord
     case StyleGeometryBox::BorderBox:
       return GetBorderRadii(aRadii);
     case StyleGeometryBox::MarginBox:
       return GetMarginBoxBorderRadii(aRadii);
     default:
       MOZ_ASSERT_UNREACHABLE("Unexpected box value");
       return false;
   }
-  return false;
 }
 
 nsStyleContext*
 nsFrame::GetAdditionalStyleContext(int32_t aIndex) const
 {
   NS_PRECONDITION(aIndex >= 0, "invalid index number");
   return nullptr;
 }