diff --git a/app/models/post.rb b/app/models/post.rb
index 32a802910..d6ea04b19 100644
--- a/app/models/post.rb
+++ b/app/models/post.rb
@@ -668,7 +668,7 @@ class Post < ActiveRecord::Base
     end
 
     def has_tag?(tag)
-      !!(tag_string =~ /(?:^| )#{tag}(?:$| )/)
+      !!(tag_string =~ /(?:^| )(?:#{tag})(?:$| )/)
     end
 
     def has_dup_tag?