diff --git a/module/story/model.php b/module/story/model.php
index 69aa0c1a49..5fedffa416 100644
--- a/module/story/model.php
+++ b/module/story/model.php
@@ -4920,7 +4920,7 @@ class storyModel extends model
         if(!empty($story->assignedTo) and $story->assignedTo != $this->app->user->account) $btnClass = $btnTextClass = 'assigned-other';
 
         $btnClass    .= $story->assignedTo == 'closed' ? ' disabled' : '';
-        $btnClass    .= 'iframe btn btn-icon-left btn-sm';
+        $btnClass    .= ' iframe btn btn-icon-left btn-sm';
         $assignToLink = helper::createLink('story', 'assignTo', "storyID=$story->id&kanbanGroup=default&from=&storyType=$story->type", '', true);
         $assignToHtml = html::a($assignToLink, "<i class='icon icon-hand-right'></i> <span>{$assignedToText}</span>", '', "class='$btnClass'");