diff --git a/framework/core/js/src/admin/components/EditCustomCssModal.js b/framework/core/js/src/admin/components/EditCustomCssModal.js
index 79a9db0bc..432961074 100644
--- a/framework/core/js/src/admin/components/EditCustomCssModal.js
+++ b/framework/core/js/src/admin/components/EditCustomCssModal.js
@@ -18,7 +18,7 @@ export default class EditCustomCssModal extends SettingsModal {
         })}
       </p>,
       <div className="Form-group">
-        <textarea className="FormControl" rows="30" bidi={this.setting('custom_less')} />
+        <textarea className="FormControl" rows="30" bidi={this.setting('custom_less')} spellcheck={false} />
       </div>,
     ];
   }