diff --git a/src/View/FormRow.php b/src/View/FormRow.php
index 6486af0..06de841 100644
--- a/src/View/FormRow.php
+++ b/src/View/FormRow.php
@@ -84,7 +84,7 @@ public function render(ElementInterface $element): string
             $rowAttributes['class'] .= ' form-row--has-errors';
         }
         if ($element->isDisabled()) {
-            $rowAttributes['class'] .= 'form-row--is-disabled';
+            $rowAttributes['class'] .= ' form-row--is-disabled';
         }
         if ($element->type() === 'hidden') {
             $rowAttributes['class'] .= ' hidden';