diff --git a/packages/client/lib/AccessTokenClient.ts b/packages/client/lib/AccessTokenClient.ts
index cd0c5b40..688c9969 100644
--- a/packages/client/lib/AccessTokenClient.ts
+++ b/packages/client/lib/AccessTokenClient.ts
@@ -175,7 +175,7 @@ export class AccessTokenClient {
       }
 
       // Default regex for alphanumeric with no specific length limit if no input_mode is specified.
-      regex = regex || /^[a-zA-Z0-9]+$/;
+      regex = regex || /^[a-zA-Z0-9]+$|^[A-Za-z0-9-_]+\.[A-Za-z0-9-_]+\.[A-Za-z0-9-_]+$/;
 
       if (!pin || !regex.test(pin)) {
         debug(
diff --git a/packages/client/lib/__tests__/IT.spec.ts b/packages/client/lib/__tests__/IT.spec.ts
index 917e690d..59292f1c 100644
--- a/packages/client/lib/__tests__/IT.spec.ts
+++ b/packages/client/lib/__tests__/IT.spec.ts
@@ -262,7 +262,7 @@ describe('OIDVCI-Client for v1_0_13 should', () => {
         issuer_state: '32fc4ebf-9e31-4149-9877-e3c0b602d559',
       },
       'urn:ietf:params:oauth:grant-type:pre-authorized_code': {
-        pre_authorized_code:
+        'pre-authorized_code':
           'eyJhbGciOiJFZERTQSJ9.eyJzdWIiOiIzMmZjNGViZi05ZTMxLTQxNDktOTg3Ny1lM2MwYjYwMmQ1NTkiLCJpc3MiOiJodHRwczovL21pam5rdmsuYWNjLmNyZWRlbmNvLmNvbSIsImF1ZCI6IlRPS0VOIn0.754aiQ87O0vHYSpRvPqAS9cLOgf-pewdeXbpLziRwsxEp9mENfaXpY62muYpzOaWcYmTOydkzhFul-NDYXJZCA',
       },
     },
@@ -324,7 +324,7 @@ describe('OIDVCI-Client for v1_0_13 should', () => {
           issuer_state: '32fc4ebf-9e31-4149-9877-e3c0b602d559',
         },
         'urn:ietf:params:oauth:grant-type:pre-authorized_code': {
-          pre_authorized_code: preAuthorizedCode,
+          'pre-authorized_code': preAuthorizedCode,
         },
       });