diff --git a/cmd/prometheus/config.go b/cmd/prometheus/config.go
index a8ac2a34a0..dbbd7ee394 100644
--- a/cmd/prometheus/config.go
+++ b/cmd/prometheus/config.go
@@ -162,6 +162,10 @@ func init() {
 		&index.LabelPairFingerprintsCacheSize, "storage.local.index-cache-size.label-pair-to-fingerprints", index.LabelPairFingerprintsCacheSize,
 		"The size in bytes for the label pair to fingerprints index cache.",
 	)
+	cfg.fs.IntVar(
+		&cfg.storage.NumMutexes, "storage.local.num-fingerprint-mutexes", 4096,
+		"The number of mutexes used for fingerprint locking.",
+	)
 
 	// Remote storage.
 	cfg.fs.StringVar(
diff --git a/storage/local/locker.go b/storage/local/locker.go
index 8ad30cc558..18fbacb9dd 100644
--- a/storage/local/locker.go
+++ b/storage/local/locker.go
@@ -37,8 +37,12 @@ type fingerprintLocker struct {
 	numFpMtxs uint
 }
 
-// newFingerprintLocker returns a new fingerprintLocker ready for use.
+// newFingerprintLocker returns a new fingerprintLocker ready for use.  At least
+// 1024 preallocated mutexes are used, even if preallocatedMutexes is lower.
 func newFingerprintLocker(preallocatedMutexes int) *fingerprintLocker {
+	if preallocatedMutexes < 1024 {
+		preallocatedMutexes = 1024
+	}
 	return &fingerprintLocker{
 		make([]sync.Mutex, preallocatedMutexes),
 		uint(preallocatedMutexes),
@@ -47,10 +51,14 @@ func newFingerprintLocker(preallocatedMutexes int) *fingerprintLocker {
 
 // Lock locks the given fingerprint.
 func (l *fingerprintLocker) Lock(fp model.Fingerprint) {
-	l.fpMtxs[uint(fp)%l.numFpMtxs].Lock()
+	l.fpMtxs[hashFP(fp)%l.numFpMtxs].Lock()
 }
 
 // Unlock unlocks the given fingerprint.
 func (l *fingerprintLocker) Unlock(fp model.Fingerprint) {
-	l.fpMtxs[uint(fp)%l.numFpMtxs].Unlock()
+	l.fpMtxs[hashFP(fp)%l.numFpMtxs].Unlock()
+}
+
+func hashFP(fp model.Fingerprint) uint {
+	return uint(fp ^ (fp >> 32) ^ (fp >> 16))
 }
diff --git a/storage/local/storage.go b/storage/local/storage.go
index 85c50d0890..fb97dd6033 100644
--- a/storage/local/storage.go
+++ b/storage/local/storage.go
@@ -184,13 +184,14 @@ type MemorySeriesStorageOptions struct {
 	PedanticChecks             bool          // If dirty, perform crash-recovery checks on each series file.
 	SyncStrategy               SyncStrategy  // Which sync strategy to apply to series files.
 	MinShrinkRatio             float64       // Minimum ratio a series file has to shrink during truncation.
+	NumMutexes                 int           // Number of mutexes used for stochastic fingerprint locking.
 }
 
 // NewMemorySeriesStorage returns a newly allocated Storage. Storage.Serve still
 // has to be called to start the storage.
 func NewMemorySeriesStorage(o *MemorySeriesStorageOptions) Storage {
 	s := &memorySeriesStorage{
-		fpLocker: newFingerprintLocker(1024),
+		fpLocker: newFingerprintLocker(o.NumMutexes),
 
 		options: o,