diff --git a/ChangeLog b/ChangeLog
index 3a2714a046..aab8ae2d37 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+Thu Oct 14 04:16:41 2010  NARUSE, Yui  <naruse@ruby-lang.org>
+
+	* numeric.c (ruby_float_step): fix Numeric#step with infinity unit
+	  doesn't works well. [ruby-core:32779]
+
 Wed Oct 13 23:16:46 2010  Nobuyoshi Nakada  <nobu@ruby-lang.org>
 
 	* tool/enc-unicode.rb: get rid of lots of warnings.
diff --git a/numeric.c b/numeric.c
index 9c82b20fe6..43d08d011d 100644
--- a/numeric.c
+++ b/numeric.c
@@ -1621,7 +1621,7 @@ ruby_float_step(VALUE from, VALUE to, VALUE step, int excl)
 	long i;
 
 	if (isinf(unit)) {
-	    if (unit > 0) rb_yield(DBL2NUM(beg));
+	    if (unit > 0 ? beg <= end : beg >= end) rb_yield(DBL2NUM(beg));
 	}
 	else {
 	    if (err>0.5) err=0.5;
diff --git a/test/ruby/test_numeric.rb b/test/ruby/test_numeric.rb
index f4fbea4ce9..9667046916 100644
--- a/test/ruby/test_numeric.rb
+++ b/test/ruby/test_numeric.rb
@@ -27,6 +27,7 @@ class TestNumeric < Test::Unit::TestCase
     assert_raise(ArgumentError) { 1 <= a }
 
     DummyNumeric.class_eval do
+      remove_method :coerce
       def coerce(x); 1.coerce(x); end
     end
     assert_equal(2, 1 + a)
@@ -34,6 +35,7 @@ class TestNumeric < Test::Unit::TestCase
     assert(1 <= a)
 
     DummyNumeric.class_eval do
+      remove_method :coerce
       def coerce(x); [x, 1]; end
     end
     assert_equal(-1, -a)
@@ -95,6 +97,7 @@ class TestNumeric < Test::Unit::TestCase
     assert_equal(:ok, a.abs)
 
     DummyNumeric.class_eval do
+      remove_method :<
       def <(x); false; end
     end
 
@@ -150,6 +153,7 @@ class TestNumeric < Test::Unit::TestCase
     assert_equal(1, a.truncate)
 
     DummyNumeric.class_eval do
+      remove_method :to_f
       def to_f; 1.4; end
     end
 
@@ -160,6 +164,7 @@ class TestNumeric < Test::Unit::TestCase
     assert_equal(1, a.truncate)
 
     DummyNumeric.class_eval do
+      remove_method :to_f
       def to_f; -1.5; end
     end
 
@@ -202,6 +207,14 @@ class TestNumeric < Test::Unit::TestCase
     a = []
     10.step(1, -(2**32)) {|x| a << x }
     assert_equal([10], a)
+
+    a = []
+    1.step(0, Float::INFINITY) {|x| a << x }
+    assert_equal([], a)
+
+    a = []
+    0.step(1, -Float::INFINITY) {|x| a << x }
+    assert_equal([], a)
   end
 
   def test_num2long
diff --git a/test/ruby/test_string.rb b/test/ruby/test_string.rb
index ed722f57f2..c024b58ed8 100644
--- a/test/ruby/test_string.rb
+++ b/test/ruby/test_string.rb
@@ -175,11 +175,11 @@ class TestString < Test::Unit::TestCase
     def o.<=>(x); nil; end
     assert_nil("foo" <=> o)
 
-    class << o;undef <=>;end
+    class << o;remove_method :<=>;end
     def o.<=>(x); 1; end
     assert_equal(-1, "foo" <=> o)
 
-    class << o;undef <=>;end
+    class << o;remove_method :<=>;end
     def o.<=>(x); 2**100; end
     assert_equal(-(2**100), "foo" <=> o)
   end
@@ -202,7 +202,7 @@ class TestString < Test::Unit::TestCase
     def o.to_str; end
     def o.==(x); false; end
     assert_equal(false, "foo" == o)
-    class << o;undef ==;end
+    class << o;remove_method :==;end
     def o.==(x); true; end
     assert_equal(true, "foo" == o)
   end
@@ -1818,7 +1818,7 @@ class TestString < Test::Unit::TestCase
       c.class_eval { attr 1 }
     end
 
-    class << o;undef to_str;end
+    class << o;remove_method :to_str;end
     def o.to_str; "foo"; end
     assert_nothing_raised do
       c.class_eval { attr o }