diff --git a/src/Templates/default/html/directives/configuration-block.html.twig b/src/Templates/default/html/directives/configuration-block.html.twig
index f4f5cbd..4917382 100644
--- a/src/Templates/default/html/directives/configuration-block.html.twig
+++ b/src/Templates/default/html/directives/configuration-block.html.twig
@@ -1,5 +1,5 @@
 <div class="configuration-block">
-    <ul class="configuration-tabs">
+    <ul class="configuration-tabs configuration-tabs-length-{{ blocks|length }}">
         {% for block in blocks %}
             <li data-language="{{ block.language }}" {{ loop.first ? 'data-active="true"' }}>
                 <span>{{ block.language_label }}</span>
diff --git a/tests/fixtures/expected/blocks/directives/configuration-block.html b/tests/fixtures/expected/blocks/directives/configuration-block.html
index 824a417..5297c83 100644
--- a/tests/fixtures/expected/blocks/directives/configuration-block.html
+++ b/tests/fixtures/expected/blocks/directives/configuration-block.html
@@ -1,5 +1,5 @@
 <div class="configuration-block">
-    <ul class="configuration-tabs">
+    <ul class="configuration-tabs configuration-tabs-length-2">
         <li data-language="yaml" data-active="true"> <span>YAML</span> </li>
         <li data-language="php" > <span>PHP</span> </li>
     </ul>
diff --git a/tests/fixtures/expected/main/datetime.html b/tests/fixtures/expected/main/datetime.html
index ae0bc98..9f3f380 100644
--- a/tests/fixtures/expected/main/datetime.html
+++ b/tests/fixtures/expected/main/datetime.html
@@ -189,7 +189,7 @@ <h3 id="error-bubbling"><a class="headerlink" href="#error-bubbling" title="Perm
 </div>
 <p>And configuration blocks:</p>
 <div class="configuration-block">
-    <ul class="configuration-tabs">
+    <ul class="configuration-tabs configuration-tabs-length-3">
         <li data-language="yaml" data-active="true"> <span>YAML</span> </li>
         <li data-language="xml" > <span>XML</span> </li>
         <li data-language="php" > <span>PHP</span> </li>