diff --git a/nipap/nipap/backend.py b/nipap/nipap/backend.py
index f8b309226..365b0ab32 100644
--- a/nipap/nipap/backend.py
+++ b/nipap/nipap/backend.py
@@ -1335,7 +1335,10 @@ def remove_vrf(self, auth, spec):
             self.remove_prefix(auth, spec = v6spec, recursive = True)
 
         where, params = self._expand_vrf_spec(spec)
-        sql = "DELETE FROM ip_net_vrf WHERE %s" % where
+        sql = """LOCK TABLE ip_net_plan IN EXCLUSIVE MODE;
+LOCK TABLE ip_net_vrf IN EXCLUSIVE MODE;
+LOCK TABLE ip_net_pool IN EXCLUSIVE MODE;
+DELETE FROM ip_net_vrf WHERE %s""" % where
         self._execute(sql, params)
 
         # write to audit table
@@ -1875,7 +1878,10 @@ def remove_pool(self, auth, spec):
         pools = self.list_pool(auth, spec)
 
         where, params = self._expand_pool_spec(spec)
-        sql = "DELETE FROM ip_net_pool AS po WHERE %s" % where
+        sql = """LOCK TABLE ip_net_plan IN EXCLUSIVE MODE;
+LOCK TABLE ip_net_vrf IN EXCLUSIVE MODE;
+LOCK TABLE ip_net_pool IN EXCLUSIVE MODE;
+DELETE FROM ip_net_pool AS po WHERE %s""" % where
         self._execute(sql, params)
 
         # write to audit table
@@ -3095,7 +3101,10 @@ def _db_remove_prefix(self, spec, recursive = False):
         else:
             where, params = self._expand_prefix_spec(spec)
 
-        sql = "DELETE FROM ip_net_plan AS p WHERE %s" % where
+        sql = """LOCK TABLE ip_net_plan IN EXCLUSIVE MODE;
+LOCK TABLE ip_net_vrf IN EXCLUSIVE MODE;
+LOCK TABLE ip_net_pool IN EXCLUSIVE MODE;
+DELETE FROM ip_net_plan AS p WHERE %s""" % where
         self._execute(sql, params)
 
 
@@ -3934,7 +3943,10 @@ def remove_asn(self, auth, asn):
 
         # remove
         where, params = self._expand_asn_spec(asn)
-        sql = "DELETE FROM ip_net_asn WHERE " + where
+        sql = """LOCK TABLE ip_net_plan IN EXCLUSIVE MODE;
+LOCK TABLE ip_net_vrf IN EXCLUSIVE MODE;
+LOCK TABLE ip_net_pool IN EXCLUSIVE MODE;
+DELETE FROM ip_net_asn WHERE """ + where
         self._execute(sql, params)
 
         # write to audit table