diff --git a/lib/gettext/runtime/textdomain.rb b/lib/gettext/runtime/textdomain.rb
index 8d519fba..bc9f413a 100644
--- a/lib/gettext/runtime/textdomain.rb
+++ b/lib/gettext/runtime/textdomain.rb
@@ -91,8 +91,9 @@ def translate_singluar_message(lang, msgid)
         # Check "aaa\000bbb" and show warning but return the singluar part.
         ret = nil
         msgid_single = msgid.split("\000")[0]
+        regex = /^#{Regexp.quote(msgid_single)}\000/
         mofile.each{|key, val|
-          if key =~ /^#{Regexp.quote(msgid_single)}\000/
+          if key =~ regex 
             # Usually, this is not caused to make po-files from rgettext.
             warn %Q[Warning: n_("#{msgid_single}", "#{msgid.split("\000")[1]}") and n_("#{key.gsub(/\000/, '", "')}") are duplicated.]
             ret = val
@@ -102,8 +103,9 @@ def translate_singluar_message(lang, msgid)
         ret
       else
         ret = nil
+        regex = /^#{Regexp.quote(msgid)}\000/
         mofile.each{|key, val|
-          if key =~ /^#{Regexp.quote(msgid)}\000/
+          if key =~ regex 
             ret = val.split("\000")[0]
             break
           end