diff --git a/src/Symfony/Bridge/Twig/Resources/views/Form/bootstrap_4_layout.html.twig b/src/Symfony/Bridge/Twig/Resources/views/Form/bootstrap_4_layout.html.twig
index 7ecc26b7b9..a1e986a39a 100644
--- a/src/Symfony/Bridge/Twig/Resources/views/Form/bootstrap_4_layout.html.twig
+++ b/src/Symfony/Bridge/Twig/Resources/views/Form/bootstrap_4_layout.html.twig
@@ -190,7 +190,9 @@
 {% block checkbox_radio_label -%}
     {#- Do not display the label if widget is not defined in order to prevent double label rendering -#}
     {%- if widget is defined -%}
-        {%- if parent_label_class is defined and ('checkbox-custom' in parent_label_class or 'radio-custom' in parent_label_class) -%}
+        {% set is_parent_custom = parent_label_class is defined and ('checkbox-custom' in parent_label_class or 'radio-custom' in parent_label_class) %}
+        {% set is_custom = label_attr.class is defined and ('checkbox-custom' in label_attr.class or 'radio-custom' in label_attr.class) %}
+        {%- if is_parent_custom or is_custom -%}
             {%- set label_attr = label_attr|merge({class: (label_attr.class|default('') ~ ' custom-control-label')|trim}) -%}
         {%- else %}
             {%- set label_attr = label_attr|merge({class: (label_attr.class|default('') ~ ' form-check-label')|trim}) -%}