diff --git a/ChangeLog b/ChangeLog
index 8cdf4eb5ea..2c8032ec1e 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+Sun Jul 10 09:46:14 2011  Masaya Tarui  <tarui@ruby-lnag.org>
+
+	* range.c (range_max): fix behavior with excluded end value.
+	  [Bug #4591]
+
 Sun Jul 10 09:13:18 2011  Eric Hodel  <drbrain@segment7.net>
 
 	* NEWS:  Fix RubyGems version.  [Ruby 1.9 - Bug #5004]
diff --git a/range.c b/range.c
index 083c70a165..b7ae19118e 100644
--- a/range.c
+++ b/range.c
@@ -665,6 +665,9 @@ range_max(VALUE range)
 		rb_raise(rb_eTypeError, "cannot exclude non Integer end value");
 	    }
 	    if (c == 0) return Qnil;
+	    if (!FIXNUM_P(b) && !rb_obj_is_kind_of(b,rb_cInteger)) {
+		rb_raise(rb_eTypeError, "cannot exclude end value with non Integer begin value");
+	    }
 	    if (FIXNUM_P(e)) {
 		return LONG2NUM(FIX2LONG(e) - 1);
 	    }
diff --git a/test/ruby/test_range.rb b/test/ruby/test_range.rb
index d45df8f820..738c7cdb85 100644
--- a/test/ruby/test_range.rb
+++ b/test/ruby/test_range.rb
@@ -68,6 +68,8 @@ class TestRange < Test::Unit::TestCase
     assert_equal(2.0, (1.0..2.0).max)
     assert_equal(nil, (2.0..1.0).max)
     assert_raise(TypeError) { (1.0...2.0).max }
+    assert_raise(TypeError) { (1...1.5).max }
+    assert_raise(TypeError) { (1.5...2).max }
 
     assert_equal(-0x80000002, ((-0x80000002)...(-0x80000001)).max)