diff --git a/html5/connect.html b/html5/connect.html
index 183db2e3..6099a9f1 100644
--- a/html5/connect.html
+++ b/html5/connect.html
@@ -1321,7 +1321,7 @@ <h4 class="panel-title">Advanced options</h4>
         }
 
         function safe_session(name) {
-          return Utilities.removeChars('a-zA-Z0-9\:-%"', name);
+          return Utilities.removeChars('a-zA-Z0-9\\:\\-%"', name);
         }
         const display = getparam("display") || "";
         function init_shadow_display() {