diff --git a/addons/web/static/src/css/base.css b/addons/web/static/src/css/base.css
index 2db16ff04b2..7eb94ad2f58 100644
--- a/addons/web/static/src/css/base.css
+++ b/addons/web/static/src/css/base.css
@@ -967,17 +967,25 @@ label.error {
 .openerp .oe_forms textarea {
     resize:vertical;
 }
-.openerp .oe_forms input[type="text"], .openerp .oe_forms input[type="password"], .openerp .oe_forms select, .openerp .oe_forms .button {
+.openerp .oe_forms input[type="text"], .openerp .oe_forms input[type="password"], .openerp .oe_forms select, .openerp .oe_forms .oe_button {
     height: 22px;
 }
 .openerp .oe_forms input.field_datetime {
     min-width: 11em;
 }
-.openerp .oe_forms .button {
+.openerp .oe_forms .oe_button {
     color: #4c4c4c;
     white-space: nowrap;
+    min-width: 100%;
+    width: 100%;
 }
-.openerp .oe_forms .button span {
+@-moz-document url-prefix() {
+    /* Strange firefox behaviour on width: 100% + white-space: nowrap */
+    .openerp .oe_forms .oe_button {
+        width: auto;
+    }
+}
+.openerp .oe_forms .oe_button span {
     position: relative;
     vertical-align: top;
 }
diff --git a/addons/web/static/src/xml/base.xml b/addons/web/static/src/xml/base.xml
index c2cb6bb814c..fb7ccdf7d8e 100644
--- a/addons/web/static/src/xml/base.xml
+++ b/addons/web/static/src/xml/base.xml
@@ -1081,7 +1081,7 @@
     </table>
 </t>
 <t t-name="WidgetButton">
-    <button type="button" style="width: 100%" class="button">
+    <button type="button" class="oe_button">
         <img t-if="widget.node.attrs.icon" t-att-src="'/web/static/src/img/icons/' + widget.node.attrs.icon + '.png'" width="16" height="16"/>
         <span t-if="widget.string"><t t-esc="widget.string"/></span>
     </button>