diff --git a/app/api/partitions.py b/app/api/partitions.py
index 50660fb66..7b47c3148 100644
--- a/app/api/partitions.py
+++ b/app/api/partitions.py
@@ -311,6 +311,13 @@ def group_create(partition_id: int):  # partition-group-create
     args["group_name"] = args["group_name"].strip()
     if not GroupDescr.check_name(partition, args["group_name"]):
         return json_error(API_CLIENT_ERROR, "invalid group_name")
+
+    # le numero est optionnel
+    numero = args.get("numero")
+    if numero is None:
+        numeros = [gr.numero or 0 for gr in partition.groups]
+        numero = (max(numeros) + 1) if numeros else 0
+        args["numero"] = numero
     args["partition_id"] = partition_id
     try:
         group = GroupDescr(**args)
diff --git a/sco_version.py b/sco_version.py
index ebe54b06f..35a788bfb 100644
--- a/sco_version.py
+++ b/sco_version.py
@@ -1,7 +1,7 @@
 # -*- mode: python -*-
 # -*- coding: utf-8 -*-
 
-SCOVERSION = "9.6.87"
+SCOVERSION = "9.6.88"
 
 SCONAME = "ScoDoc"