diff --git a/specs/insights/common/schemas/EventAttributes.yml b/specs/insights/common/schemas/EventAttributes.yml
index f61bca3a73..ff78563f5a 100644
--- a/specs/insights/common/schemas/EventAttributes.yml
+++ b/specs/insights/common/schemas/EventAttributes.yml
@@ -19,7 +19,7 @@ index:
 userToken:
   type: string
   minLength: 1
-  maxLength: 128
+  maxLength: 129
   pattern: '[a-zA-Z0-9_=/+-]{1,129}'
   description: |
     Anonymous or pseudonymous user identifier.