diff --git a/tools/migratedb/import_redis.py b/tools/migratedb/import_redis.py
index 52888c2..45a6eeb 100644
--- a/tools/migratedb/import_redis.py
+++ b/tools/migratedb/import_redis.py
@@ -30,7 +30,8 @@ def writeToRedis(conn, cmdline):
         else:
             print('[warning]', cmdline)
     elif cmdline[0] == 'expire':
-        conn.expire(cmdline[1], cmdline[2])
+        if int(cmdline[2]) >= 0:
+            conn.expire(cmdline[1], cmdline[2])
     else:
         assert False