--- a/gfx/2d/BasePoint.h
+++ b/gfx/2d/BasePoint.h
@@ -73,17 +73,17 @@ struct BasePoint {
   Sub operator-() const {
     return Sub(-x, -y);
   }
 
   T DotProduct(const Sub& aPoint) const {
       return x * aPoint.x + y * aPoint.y;
   }
 
-  T Length() const {
+  Coord Length() const {
     return hypot(x, y);
   }
 
   T LengthSquare() const {
     return x * x + y * y;
   }
 
   // Round() is *not* rounding to nearest integer if the values are negative.