diff --git a/apps/knowledge/models/knowledge.py b/apps/knowledge/models/knowledge.py
index aa1ef7f6b..49458eda9 100644
--- a/apps/knowledge/models/knowledge.py
+++ b/apps/knowledge/models/knowledge.py
@@ -280,6 +280,7 @@ class File(AppModelMixin):
         else:
             result = select_one("SELECT lo_from_bytea(%s, %s::bytea) as loid", [0, bytea])
             self.loid = result['loid']
+        self.file_size = len(bytea)
         super().save()
 
     def get_bytes(self):