diff --git a/core/stores/redis/redislock.go b/core/stores/redis/redislock.go
index 3e85d972..69077850 100644
--- a/core/stores/redis/redislock.go
+++ b/core/stores/redis/redislock.go
@@ -16,9 +16,7 @@ const (
 else
     return 0
 end`
-	randomLen       = 16
-	tolerance       = 500 // milliseconds
-	millisPerSecond = 1000
+	randomLen = 16
 )
 
 // A RedisLock is a redis lock.
@@ -51,7 +49,7 @@ func (rl *RedisLock) Acquire() (bool, error) {
 	}
 
 	seconds := atomic.LoadUint32(&rl.seconds)
-	ok, err := rl.store.SetnxEx(rl.key, rl.id, int(seconds))
+	ok, err := rl.store.SetnxEx(rl.key, rl.id, int(seconds+1)) // +1s for tolerance
 	if err == red.Nil {
 		atomic.AddInt32(&rl.count, -1)
 		return false, nil
@@ -65,7 +63,6 @@ func (rl *RedisLock) Acquire() (bool, error) {
 	}
 
 	return true, nil
-
 }
 
 // Release releases the lock.
diff --git a/core/stores/redis/redislock_test.go b/core/stores/redis/redislock_test.go
index d12ed03e..2234f403 100644
--- a/core/stores/redis/redislock_test.go
+++ b/core/stores/redis/redislock_test.go
@@ -49,6 +49,5 @@ func TestRedisLock(t *testing.T) {
 		firstAcquire, err = firstLock.Acquire()
 		assert.Nil(t, err)
 		assert.True(t, firstAcquire)
-
 	})
 }