diff --git a/compar.c b/compar.c
index 81dff38f49..3d0a3e81dc 100644
--- a/compar.c
+++ b/compar.c
@@ -20,7 +20,7 @@ rb_cmperr(VALUE x, VALUE y)
 {
     VALUE classname;
 
-    if (SPECIAL_CONST_P(y)) {
+    if (SPECIAL_CONST_P(y) || BUILTIN_TYPE(y) == T_FLOAT) {
 	classname = rb_inspect(y);
     }
     else {