diff --git a/protocol-definitions/custom/Custom.yaml b/protocol-definitions/custom/Custom.yaml
index 52d88d4e..2c0edc55 100644
--- a/protocol-definitions/custom/Custom.yaml
+++ b/protocol-definitions/custom/Custom.yaml
@@ -988,7 +988,7 @@ customTypes:
       - name: autoStepDownWhenLeader
         type: boolean
         nullable: false
-        since: 2.9
+        since: "2.10"
   - name: MigrationState
     since: 2.2
     params: