diff --git a/internal/server/follow.go b/internal/server/follow.go
index a70c2204..e61759f9 100644
--- a/internal/server/follow.go
+++ b/internal/server/follow.go
@@ -302,6 +302,7 @@ func (s *Server) followStep(host string, port int, followc int) error {
 		if !caughtUp {
 			if aofsz >= int(aofSize) {
 				caughtUp = true
+				s.mu.Lock()
 				s.flushAOF(false)
 				s.fcup = true
 				s.fcuponce = true