diff --git a/src/3p-filters.html b/src/3p-filters.html
index aed39680e..891595848 100644
--- a/src/3p-filters.html
+++ b/src/3p-filters.html
@@ -25,7 +25,7 @@
 <div id="externalListsDiv">
 <p data-i18n="3pExternalListsHint" style="margin: 0 0 0.25em 0; font-size: 13px;"></p>
 <textarea id="externalLists" dir="ltr" spellcheck="false"></textarea>
-<p style="margin: 0.25em 0 0 0"><button id="externalListsApply" disabled="true" data-i18n="3pExternalListsApply"></button></p>
+<p style="margin: 0.25em 0 0 0"><button id="externalListsApply" class="important" disabled="true" data-i18n="3pExternalListsApply"></button></p>
 </div>
 
 <div id="busyOverlay">