diff --git a/fastcache.go b/fastcache.go
index 342b67d..daa3db7 100644
--- a/fastcache.go
+++ b/fastcache.go
@@ -271,20 +271,18 @@ func (b *bucket) Reset() {
 	b.mu.Unlock()
 }
 
-func (b *bucket) Clean() {
-	b.mu.Lock()
+func (b *bucket) cleanLocked() {
 	bGen := b.gen & ((1 << genSizeBits) - 1)
 	bIdx := b.idx
 	bm := b.m
 	for k, v := range bm {
 		gen := v >> bucketSizeBits
 		idx := v & ((1 << bucketSizeBits) - 1)
-		if gen == bGen && idx < bIdx || gen+1 == bGen && idx >= bIdx || gen == maxGen && bGen == 1 && idx >= bIdx {
+		if (gen+1 == bGen || gen == maxGen && bGen == 1) && idx >= bIdx || gen == bGen && idx < bIdx {
 			continue
 		}
 		delete(bm, k)
 	}
-	b.mu.Unlock()
 }
 
 func (b *bucket) UpdateStats(s *Stats) {
@@ -296,19 +294,17 @@ func (b *bucket) UpdateStats(s *Stats) {
 
 	b.mu.RLock()
 	s.EntriesCount += uint64(len(b.m))
+	bytesSize := uint64(0)
 	for _, chunk := range b.chunks {
-		s.BytesSize += uint64(cap(chunk))
+		bytesSize += uint64(cap(chunk))
 	}
-	s.MaxBytesSize += uint64(len(b.chunks))*chunkSize
+	s.BytesSize += bytesSize
+	s.MaxBytesSize += uint64(len(b.chunks)) * chunkSize
 	b.mu.RUnlock()
 }
 
 func (b *bucket) Set(k, v []byte, h uint64) {
-	setCalls := atomic.AddUint64(&b.setCalls, 1)
-	if setCalls%(1<<14) == 0 {
-		b.Clean()
-	}
-
+	atomic.AddUint64(&b.setCalls, 1)
 	if len(k) >= (1<<16) || len(v) >= (1<<16) {
 		// Too big key or value - its length cannot be encoded
 		// with 2 bytes (see below). Skip the entry.
@@ -326,13 +322,15 @@ func (b *bucket) Set(k, v []byte, h uint64) {
 		return
 	}
 
+	chunks := b.chunks
+	needClean := false
 	b.mu.Lock()
 	idx := b.idx
 	idxNew := idx + kvLen
 	chunkIdx := idx / chunkSize
 	chunkIdxNew := idxNew / chunkSize
 	if chunkIdxNew > chunkIdx {
-		if chunkIdxNew >= uint64(len(b.chunks)) {
+		if chunkIdxNew >= uint64(len(chunks)) {
 			idx = 0
 			idxNew = kvLen
 			chunkIdx = 0
@@ -340,14 +338,15 @@ func (b *bucket) Set(k, v []byte, h uint64) {
 			if b.gen&((1<<genSizeBits)-1) == 0 {
 				b.gen++
 			}
+			needClean = true
 		} else {
 			idx = chunkIdxNew * chunkSize
 			idxNew = idx + kvLen
 			chunkIdx = chunkIdxNew
 		}
-		b.chunks[chunkIdx] = b.chunks[chunkIdx][:0]
+		chunks[chunkIdx] = chunks[chunkIdx][:0]
 	}
-	chunk := b.chunks[chunkIdx]
+	chunk := chunks[chunkIdx]
 	if chunk == nil {
 		chunk = getChunk()
 		chunk = chunk[:0]
@@ -355,15 +354,19 @@ func (b *bucket) Set(k, v []byte, h uint64) {
 	chunk = append(chunk, kvLenBuf[:]...)
 	chunk = append(chunk, k...)
 	chunk = append(chunk, v...)
-	b.chunks[chunkIdx] = chunk
+	chunks[chunkIdx] = chunk
 	b.m[h] = idx | (b.gen << bucketSizeBits)
 	b.idx = idxNew
+	if needClean {
+		b.cleanLocked()
+	}
 	b.mu.Unlock()
 }
 
 func (b *bucket) Get(dst, k []byte, h uint64, returnDst bool) ([]byte, bool) {
 	atomic.AddUint64(&b.getCalls, 1)
 	found := false
+	chunks := b.chunks
 	b.mu.RLock()
 	v := b.m[h]
 	bGen := b.gen & ((1 << genSizeBits) - 1)
@@ -372,12 +375,12 @@ func (b *bucket) Get(dst, k []byte, h uint64, returnDst bool) ([]byte, bool) {
 		idx := v & ((1 << bucketSizeBits) - 1)
 		if gen == bGen && idx < b.idx || gen+1 == bGen && idx >= b.idx || gen == maxGen && bGen == 1 && idx >= b.idx {
 			chunkIdx := idx / chunkSize
-			if chunkIdx >= uint64(len(b.chunks)) {
+			if chunkIdx >= uint64(len(chunks)) {
 				// Corrupted data during the load from file. Just skip it.
 				atomic.AddUint64(&b.corruptions, 1)
 				goto end
 			}
-			chunk := b.chunks[chunkIdx]
+			chunk := chunks[chunkIdx]
 			idx %= chunkSize
 			if idx+4 >= chunkSize {
 				// Corrupted data during the load from file. Just skip it.
diff --git a/file.go b/file.go
index bab5484..dfbc070 100644
--- a/file.go
+++ b/file.go
@@ -272,7 +272,9 @@ func loadBuckets(buckets []bucket, dataPath string, maxChunks uint64) error {
 }
 
 func (b *bucket) Save(w io.Writer) error {
-	b.Clean()
+	b.mu.Lock()
+	b.cleanLocked()
+	b.mu.Unlock()
 
 	b.mu.RLock()
 	defer b.mu.RUnlock()
diff --git a/malloc_heap.go b/malloc_heap.go
index 79a7183..810d460 100644
--- a/malloc_heap.go
+++ b/malloc_heap.go
@@ -1,3 +1,4 @@
+//go:build appengine || windows
 // +build appengine windows
 
 package fastcache
diff --git a/malloc_mmap.go b/malloc_mmap.go
index e0cd0e7..e24d578 100644
--- a/malloc_mmap.go
+++ b/malloc_mmap.go
@@ -1,3 +1,4 @@
+//go:build !appengine && !windows
 // +build !appengine,!windows
 
 package fastcache