diff --git a/cdc/entry/schema/snapshot.go b/cdc/entry/schema/snapshot.go
index b188ffcf5a7..0e1971e8c64 100644
--- a/cdc/entry/schema/snapshot.go
+++ b/cdc/entry/schema/snapshot.go
@@ -570,6 +570,9 @@ func (s *Snapshot) SchemaCount() (count int) {
 
 // DumpToString dumps the snapshot to a string.
 func (s *Snapshot) DumpToString() string {
+	s.rwlock.RLock()
+	defer s.rwlock.RUnlock()
+
 	schemas := make([]string, 0, s.inner.schemas.Len())
 	s.IterSchemas(func(dbInfo *timodel.DBInfo) {
 		schemas = append(schemas, fmt.Sprintf("%v", dbInfo))