diff --git a/app/scripts/templates/sign_in_token_code.mustache b/app/scripts/templates/sign_in_token_code.mustache
index d59e58cd3..c9dbaaee6 100644
--- a/app/scripts/templates/sign_in_token_code.mustache
+++ b/app/scripts/templates/sign_in_token_code.mustache
@@ -15,7 +15,7 @@
 
     <form novalidate>
       <div class="input-row token-code-row">
-        <input type="number" class="tooltip-below token-code" placeholder="{{#t}}Enter code{{/t}}" required autofocus />
+        <input type="number" pattern="\d*" class="tooltip-below token-code" placeholder="{{#t}}Enter code{{/t}}" required autofocus />
       </div>
 
       <div class="button-row">