diff --git a/core/config/schema/core.data_types.schema.yml b/core/config/schema/core.data_types.schema.yml
index 1dac4c3..9314121 100644
--- a/core/config/schema/core.data_types.schema.yml
+++ b/core/config/schema/core.data_types.schema.yml
@@ -424,7 +424,7 @@ core.date_format.*:
       type: core_date_format_pattern.[%parent.locked]
       label: 'PHP date format'
 
-core_date_format_pattern.:
+core_date_format_pattern.0:
   type: date_format
   label: 'Date format'
 
diff --git a/core/lib/Drupal/Core/Config/TypedConfigManager.php b/core/lib/Drupal/Core/Config/TypedConfigManager.php
index 6bd33cc..db08753 100644
--- a/core/lib/Drupal/Core/Config/TypedConfigManager.php
+++ b/core/lib/Drupal/Core/Config/TypedConfigManager.php
@@ -283,8 +283,12 @@ protected function replaceVariable($value, $data) {
         return $value;
       }
       elseif (!$parts) {
+        $value = $data[$name];
+        if (is_bool($value)) {
+          $value = (int) $value;
+        }
         // If no more parts left, this is the final property.
-        return (string)$data[$name];
+        return (string) $value;
       }
       else {
         // Get nested value and continue processing.