diff --git a/lib/ecdsa/group.rb b/lib/ecdsa/group.rb
index <HASH>..<HASH> 100644
--- a/lib/ecdsa/group.rb
+++ b/lib/ecdsa/group.rb
@@ -77,7 +77,7 @@ module ECDSA
 
     # You should probably use include? instead of this.
     def point_satisfies_equation?(point)
-      field.mod(point.y * point.y) == equation_right_hand_side(point.x)
+      field.square(point.y) == equation_right_hand_side(point.x)
     end
 
     def equation_right_hand_side(x)
Simplified Group#point_satisfies_equation? by using field.square for the left-hand side.