diff --git a/systemvm/patches/debian/config/opt/cloud/bin/cs_ip.py b/systemvm/patches/debian/config/opt/cloud/bin/cs_ip.py
index 5b980ef2be1..8820354da08 100755
--- a/systemvm/patches/debian/config/opt/cloud/bin/cs_ip.py
+++ b/systemvm/patches/debian/config/opt/cloud/bin/cs_ip.py
@@ -45,7 +45,7 @@ def merge(dbag, ip):
     if ip['nw_type'] == 'control':
         dbag[ip['device']] = [ip]
     else:
-        if index != -1:
+        if index != -1 and ip['device'] in dbag and index in dbag[ip['device']]:
             dbag[ip['device']][index] = ip
         else:
             dbag.setdefault(ip['device'], []).append(ip)