diff --git a/www/common/outer/calendar.js b/www/common/outer/calendar.js
index 1b3f02231..21bff21ff 100644
--- a/www/common/outer/calendar.js
+++ b/www/common/outer/calendar.js
@@ -1055,7 +1055,7 @@ define([
 
     var removeClient = function (ctx, cId) {
         var idx = ctx.clients.indexOf(cId);
-        ctx.clients.splice(idx, 1);
+        if (idx !== -1) { ctx.clients.splice(idx, 1); }
 
         Object.keys(ctx.calendars).forEach(function (id) {
             var cal = ctx.calendars[id];