diff --git a/src/plugins/kibana/public/discover/styles/main.less b/src/plugins/kibana/public/discover/styles/main.less
index 25dba9ba3bee..13b53fc815b1 100644
--- a/src/plugins/kibana/public/discover/styles/main.less
+++ b/src/plugins/kibana/public/discover/styles/main.less
@@ -240,7 +240,7 @@ field-name,
 disc-field-chooser {
   ul.discover-selected-fields {
     /* If only _source is presend in the selected fields list, hide its toggle button */
-    li:first-child:nth-last-child(1)[field=_source] button.discover-field-toggle {
+    li:first-child:nth-last-child(1)[attr-field=_source] button.discover-field-toggle {
       display: none;
     }
   }