diff --git a/ChangeLog b/ChangeLog
index 095fef2d01..826bebf9c4 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,11 @@
+Mon Jul 23 01:47:26 2012  Kazuhiro NISHIYAMA  <zn@mbf.nifty.com>
+
+	* test/uri/test_generic.rb (URI#with_env): unset proxy related env
+	  variables.  [Bug #6774]
+
+	* test/uri/test_generic.rb (URI#test_find_proxy): fix failures
+	  when proxy related env variables already set.  [Bug #6774]
+
 Sun Jul 22 23:58:48 2012  NARUSE, Yui  <naruse@ruby-lang.org>
 
 	* thread.c (rb_threadptr_execute_interrupts_common): increase
diff --git a/test/uri/test_generic.rb b/test/uri/test_generic.rb
index d3a39e823e..9c0b6051a7 100644
--- a/test/uri/test_generic.rb
+++ b/test/uri/test_generic.rb
@@ -736,8 +736,10 @@ class URI::TestGeneric < Test::Unit::TestCase
   # 192.0.2.0/24 is TEST-NET.  [RFC3330]
 
   def test_find_proxy
-    assert_nil(URI("http://192.0.2.1/").find_proxy)
-    assert_nil(URI("ftp://192.0.2.1/").find_proxy)
+    with_env({}) {
+      assert_nil(URI("http://192.0.2.1/").find_proxy)
+      assert_nil(URI("ftp://192.0.2.1/").find_proxy)
+    }
     with_env('http_proxy'=>'http://127.0.0.1:8080') {
       assert_equal(URI('http://127.0.0.1:8080'), URI("http://192.0.2.1/").find_proxy)
       assert_nil(URI("ftp://192.0.2.1/").find_proxy)
@@ -771,6 +773,11 @@ class URI::TestGeneric < Test::Unit::TestCase
   end unless RUBY_PLATFORM =~ /mswin|mingw/
 
   def with_env(h)
+    ['http', 'https', 'ftp'].each do |scheme|
+      name = "#{scheme}_proxy"
+      h[name] ||= nil
+      h["CGI_#{name.upcase}"] ||= nil
+    end
     begin
       old = {}
       h.each_key {|k| old[k] = ENV[k] }