diff --git a/store/mockstore/unistore/tikv/region.go b/store/mockstore/unistore/tikv/region.go
index 932841c968927..d854c910047a9 100644
--- a/store/mockstore/unistore/tikv/region.go
+++ b/store/mockstore/unistore/tikv/region.go
@@ -248,7 +248,13 @@ func (ri *regionCtx) AcquireLatches(hashVals []uint64) {
 	dur := time.Since(start)
 	metrics.LatchWait.Observe(dur.Seconds())
 	if dur > time.Millisecond*50 {
-		log.S().Warnf("region %d acquire %d locks takes %v, waitCnt %d", ri.meta.Id, len(hashVals), dur, waitCnt)
+		var id string
+		if ri.meta == nil {
+			id = "unknown"
+		} else {
+			id = strconv.FormatUint(ri.meta.Id, 10)
+		}
+		log.S().Warnf("region %s acquire %d locks takes %v, waitCnt %d", id, len(hashVals), dur, waitCnt)
 	}
 }