diff -u b/core/config/schema/core.data_types.schema.yml b/core/config/schema/core.data_types.schema.yml
--- b/core/config/schema/core.data_types.schema.yml
+++ b/core/config/schema/core.data_types.schema.yml
@@ -445,7 +445,7 @@
     case_sensitive:
       type: boolean
       label: 'Case sensitive'
-      is_alphanumeric:
+    is_alphanumeric:
       type: boolean
       label: 'US ASCII characters only'