diff --git a/ChangeLog b/ChangeLog
index 7a3ef1d7e0..8789818793 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+Tue Jun  8 15:34:15 2010  Nobuyoshi Nakada  <nobu@ruby-lang.org>
+
+	* file.c (rb_file_s_extname): skip last directory separators.
+	  [ruby-core:29627]
+
 Tue Jun  8 15:33:30 2010  URABE Shyouhei  <shyouhei@ruby-lang.org>
 
 	* lib/fileutils.rb (FileUtils::cp_r): dup needed here; options are
diff --git a/file.c b/file.c
index acb6a548b9..9452d046d9 100644
--- a/file.c
+++ b/file.c
@@ -3024,7 +3024,7 @@ rb_file_s_extname(klass, fname)
     if (!p)
 	p = name;
     else
-	name = ++p;
+	do name = ++p; while (isdirsep(*p));
 
     e = 0;
     while (*p) {
diff --git a/test/ruby/test_file_exhaustive.rb b/test/ruby/test_file_exhaustive.rb
index ca3227d832..eb4c77fc54 100644
--- a/test/ruby/test_file_exhaustive.rb
+++ b/test/ruby/test_file_exhaustive.rb
@@ -403,6 +403,8 @@ class TestFileExhaustive < Test::Unit::TestCase
         end
       end
     end
+    bug3175 = '[ruby-core:29627]'
+    assert_equal(".rb", File.extname("/tmp//bla.rb"), bug3175)
   end
 
   def test_split
diff --git a/version.h b/version.h
index 82297f7034..175774c67c 100644
--- a/version.h
+++ b/version.h
@@ -2,7 +2,7 @@
 #define RUBY_RELEASE_DATE "2010-06-08"
 #define RUBY_VERSION_CODE 187
 #define RUBY_RELEASE_CODE 20100608
-#define RUBY_PATCHLEVEL 276
+#define RUBY_PATCHLEVEL 277
 
 #define RUBY_VERSION_MAJOR 1
 #define RUBY_VERSION_MINOR 8