1 files changed, 1 insertions, 1 deletions
diff --git a/class.c b/class.c
index 2ee5b8867a..1d871fb7ee 100644
--- a/class.c
+++ b/class.c
@@ -1315,7 +1315,7 @@ singleton_class_of(VALUE obj)
 {
     VALUE klass;
 
-    if (FIXNUM_P(obj) || SYMBOL_P(obj)) {
+    if (FIXNUM_P(obj) || FLONUM_P(obj) || SYMBOL_P(obj)) {
 	rb_raise(rb_eTypeError, "can't define singleton");
     }
     if (SPECIAL_CONST_P(obj)) {