diff --git a/gfx/2d/Point.h b/gfx/2d/Point.h
index f66967622f..96b2d8d5cf 100644
--- a/gfx/2d/Point.h
+++ b/gfx/2d/Point.h
@@ -285,7 +285,7 @@ typedef IntSizeTyped<UnknownUnits> IntSize;
 
 template<class units, class F = Float>
 struct SizeTyped :
-  public BaseSize< F, SizeTyped<units> >,
+  public BaseSize< F, SizeTyped<units, F> >,
   public units {
   static_assert(IsPixel<units>::value,
                 "'units' must be a coordinate system tag");