diff --git a/schemas/digitalIdentifier/ISBN.schema.tpl.json b/schemas/digitalIdentifier/ISBN.schema.tpl.json
index 4acbc3b5..587f1a27 100644
--- a/schemas/digitalIdentifier/ISBN.schema.tpl.json
+++ b/schemas/digitalIdentifier/ISBN.schema.tpl.json
@@ -9,7 +9,7 @@
   "properties": {
     "identifier": {
       "type": "string",
-      "pattern": "^([0-9]{3}-|)[0-9]{1}-[0-9]{3}-[0-9]{5}-[0-9]{1}$",
+      "pattern": "^([0-9]{3}-)?[0-9]{1}-[0-9]{3}-[0-9]{5}-[0-9]{1}|[0-9]{1}-[0-9]{2}-[0-9]{6}-[0-9]{1}$",
       "_instruction": "Enter the numeric commercial book identifier 'International Standard Book Number' (ISBN) following the defined pattern (e.g., 123-4-567-89012-3 (13-digit ISBN) or 4-567-89012-3 (10-digit ISBN))."
     }
   }