diff --git a/ChangeLog b/ChangeLog
index c1853c37c3..f43646a6e5 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+Thu Jul  1 22:15:01 2010  Tanaka Akira  <akr@fsij.org>
+
+	* numeric.c (rb_num2ulong): fix the lower limit for float.
+	  [ruby-dev:41361]
+
 Thu Jul  1 21:37:11 2010  Nobuyoshi Nakada  <nobu@ruby-lang.org>
 
 	* test/ruby/envutil.rb (EnvUtil#invoke_ruby): integrated with
diff --git a/numeric.c b/numeric.c
index 9ff193c0d5..993e1c46cf 100644
--- a/numeric.c
+++ b/numeric.c
@@ -1729,7 +1729,7 @@ rb_num2ulong(VALUE val)
 
     switch (TYPE(val)) {
       case T_FLOAT:
-       if (RFLOAT_VALUE(val) <= (double)LONG_MAX
+       if (RFLOAT_VALUE(val) <= (double)ULONG_MAX
            && RFLOAT_VALUE(val) >= (double)LONG_MIN) {
            return (VALUE)RFLOAT_VALUE(val);
        }