diff --git a/ChangeLog b/ChangeLog
index ae44e78314..894a671f39 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+Mon May 30 00:09:37 2016  NAKAMURA Usaku  <usa@ruby-lang.org>
+
+	* ext/-test-/auto_ext.rb: fixed a heedless bug introduced at r55198.
+	  this change will make RubyCI green.
+
 Sun May 29 22:58:19 2016  NARUSE, Yui  <naruse@ruby-lang.org>
 
 	* regexec.c (ONIGENC_IS_MBC_ASCII_WORD): redefine optimized one.
diff --git a/ext/-test-/auto_ext.rb b/ext/-test-/auto_ext.rb
index 5f840c4841..71606a9dd1 100644
--- a/ext/-test-/auto_ext.rb
+++ b/ext/-test-/auto_ext.rb
@@ -1,5 +1,5 @@
 # frozen_string_literal: false
-def auto_ext(feat = $0[%r[/ext/-test-/(.*)/extconf.rb\z], 1], inc: false)
+def auto_ext(feat = $0[%r[/ext/(-test-/.*)/extconf.rb\z], 1], inc: false)
   $INCFLAGS << " -I$(topdir) -I$(top_srcdir)" if inc
   $srcs = Dir[File.join($srcdir, "*.{#{SRC_EXT.join(%q{,})}}")]
   inits = $srcs.map {|s| File.basename(s, ".*")}