diff --git a/ereuse_devicehub/migrations/versions/bf600ca861a4_adding_hid.py b/ereuse_devicehub/migrations/versions/bf600ca861a4_adding_hid.py
index 662671c6..ae68e3ed 100644
--- a/ereuse_devicehub/migrations/versions/bf600ca861a4_adding_hid.py
+++ b/ereuse_devicehub/migrations/versions/bf600ca861a4_adding_hid.py
@@ -40,6 +40,8 @@ def upgrade():
     macs = {}
     for c in computers:
         hids[c.id] = c.hid
+        if not c.serial_number:
+            continue
         try:
             macs[c.id].append(c.serial_number)
             macs[c.id].sort()
@@ -52,8 +54,6 @@ def upgrade():
         if not id_dev in macs:
             continue
         mac = macs[id_dev][0]
-        if not mac:
-            continue
         new_hid = "{}-{}".format(hid, mac)
 
         sql = f"update {get_inv()}.device set hid='{new_hid}' where id={id_dev};"