diff --git a/zproject/urls.py b/zproject/urls.py
index 4af0f1eca2..4a03099723 100644
--- a/zproject/urls.py
+++ b/zproject/urls.py
@@ -207,7 +207,7 @@ v1_api_and_json_patterns = [
     # reactions -> zerver.view.reactions
     # PUT adds a reaction to a message
     # DELETE removes a reaction from a message
-    url(r'^messages/(?P<message_id>[0-9]+)/emoji_reactions/(?P<emoji_name>[0-9a-zA-Z.\-_]+(?<![.\-_]))$',
+    url(r'^messages/(?P<message_id>[0-9]+)/emoji_reactions/(?P<emoji_name>[+0-9a-zA-Z.\-_]+(?<![.\-_]))$',
         rest_dispatch,
         {'PUT': 'zerver.views.reactions.add_reaction_backend',
          'DELETE': 'zerver.views.reactions.remove_reaction_backend'}),