diff --git a/addons/web/static/src/css/base.css b/addons/web/static/src/css/base.css
index 0994ed41b1a..32c7f14b345 100644
--- a/addons/web/static/src/css/base.css
+++ b/addons/web/static/src/css/base.css
@@ -1418,7 +1418,7 @@ label.error {
 }
 @-moz-document url-prefix() {
     /* Strange firefox behaviour on width: 100% + white-space: nowrap */
-    .openerp .oe_forms .oe_button {
+    .openerp .oe_forms .oe_form_button .oe_button {
         width: auto;
     }
 }