diff --git a/Include/mymath.h b/Include/mymath.h
index 3a8c62e..7873a3d 100644
--- a/Include/mymath.h
+++ b/Include/mymath.h
@@ -10,7 +10,7 @@
 #endif
 
 #ifndef HAVE_HYPOT
-extern double hypot Py_PROTO((double, double));
+extern double hypot(double, double);
 #ifdef MWERKS_BEFORE_PRO4
 #define hypot we_dont_want_faulty_hypot_decl
 #endif