diff --git a/models/application/document.json b/models/application/document.json
index 82321023b07265dea00dd1f664c6cb63d79b6add..fcab2fed0c5e242fc9280f582f216c2b333bfda7 100644
--- a/models/application/document.json
+++ b/models/application/document.json
@@ -73,7 +73,7 @@
         "digest": {
           "type": "string",
           "description": "Prüfsumme, hexadezimal codiert",
-          "pattern": "[0-9A-F]{64,128}"
+          "pattern": "^[A-Fa-f0-9]{64}([A-Fa-f0-9]{64})?$"
         }
       },
       "required": [