diff --git a/storage/local/storage.go b/storage/local/storage.go
index 62453d89d..b10708b20 100644
--- a/storage/local/storage.go
+++ b/storage/local/storage.go
@@ -18,6 +18,7 @@ import (
 	"container/list"
 	"fmt"
 	"math"
+	"sync"
 	"sync/atomic"
 	"time"
 
@@ -124,6 +125,7 @@ type memorySeriesStorage struct {
 	numChunksToPersist int64         // The number of chunks waiting for persistence.
 	maxChunksToPersist int           // If numChunksToPersist reaches this threshold, ingestion will be throttled.
 	rushed             bool          // Whether the storage is in rushed mode.
+	rushedMtx          sync.Mutex    // Protects entering and exiting rushed mode.
 	throttled          chan struct{} // This chan is sent to whenever NeedsThrottling() returns true (for logging).
 
 	fpLocker   *fingerprintLocker
@@ -1248,6 +1250,9 @@ func (s *memorySeriesStorage) incNumChunksToPersist(by int) {
 // files should not by synced anymore provided the user has specified the
 // adaptive sync strategy.
 func (s *memorySeriesStorage) calculatePersistenceUrgencyScore() float64 {
+	s.rushedMtx.Lock()
+	defer s.rushedMtx.Unlock()
+
 	var (
 		chunksToPersist    = float64(s.getNumChunksToPersist())
 		maxChunksToPersist = float64(s.maxChunksToPersist)