diff --git a/apps/wpm/scripts/wpr_bxerp.py b/apps/wpm/scripts/wpr_bxerp.py
index b14b4f5a..7fb8994c 100644
--- a/apps/wpm/scripts/wpr_bxerp.py
+++ b/apps/wpm/scripts/wpr_bxerp.py
@@ -25,7 +25,7 @@ def main(number, mgroup:Mgroup):
     
     old_data:dict = wpr.data
     if old_data:
-        for item in old_data.keys():
+        for item in list(old_data.keys()):
             if f'{mgroup_name}_' in item:
                 del old_data[item]
     old_data.update(data)