diff --git a/ChangeLog b/ChangeLog
index 87e2037c00..d5a23be544 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,9 @@
+Wed Dec 12 21:40:45 2012  Nobuyoshi Nakada  <nobu@ruby-lang.org>
+
+	* lib/tmpdir.rb (Dir::Tmpname#create): deal with a prefix name which
+	  starts with tilde as a plain name, not expanding as home directory.
+	  [ruby-core:50793] [Bug #7547]
+
 Wed Dec 12 19:48:59 2012  NARUSE, Yui  <naruse@ruby-lang.org>
 
 	* ext/json: merge JSON 1.7.5.
diff --git a/lib/tmpdir.rb b/lib/tmpdir.rb
index 03c02fd788..18d4fb683d 100644
--- a/lib/tmpdir.rb
+++ b/lib/tmpdir.rb
@@ -138,7 +138,7 @@ class Dir
       end
       n = nil
       begin
-        path = File.expand_path(make_tmpname(basename, n), tmpdir)
+        path = File.join(tmpdir, make_tmpname(basename, n))
         yield(path, n, *opts)
       rescue Errno::EEXIST
         n ||= 0
diff --git a/test/test_tmpdir.rb b/test/test_tmpdir.rb
index c48b4b7fb2..61d3f60213 100644
--- a/test/test_tmpdir.rb
+++ b/test/test_tmpdir.rb
@@ -18,4 +18,15 @@ class TestTmpdir < Test::Unit::TestCase
       end
     end
   end
+
+  def test_no_homedir
+    bug7547 = '[ruby-core:50793]'
+    home, ENV["HOME"] = ENV["HOME"], nil
+    dir = assert_nothing_raised(bug7547) do
+      break Dir.mktmpdir("~")
+    end
+    assert_match(/\A~/, File.basename(dir), bug7547)
+  ensure
+    ENV["HOME"] = home
+  end
 end