diff --git a/templates/system/input.vars.php b/templates/system/input.vars.php
index 4deed1b..e25e057 100644
--- a/templates/system/input.vars.php
+++ b/templates/system/input.vars.php
@@ -6,6 +6,10 @@
 
 use Drupal\Core\Template\Attribute;
 
+function bootstrap_preprocess_input__button(&$variables) {
+  bootstrap_preprocess_input($variables);
+}
+
 /**
  * Preprocess input.
  */