diff --git a/admin/code/LeftAndMain.php b/admin/code/LeftAndMain.php
index 2634a6c70..f1b3d4a9d 100644
--- a/admin/code/LeftAndMain.php
+++ b/admin/code/LeftAndMain.php
@@ -556,7 +556,7 @@ class LeftAndMain extends Controller implements PermissionProvider {
 		$icon = Config::inst()->get($class, 'menu_icon', Config::FIRST_SET);
 		if (!empty($icon)) {
 			$class = strtolower(Convert::raw2htmlname(str_replace('\\', '-', $class)));
-			return ".icon.icon-16.icon-{$class} { background: url('{$icon}'); } ";
+			return ".icon.icon-16.icon-{$class} { background-image: url('{$icon}'); } ";
 		}
 		return '';
 	}