diff --git a/compress/decompress.go b/compress/decompress.go
index af32596bc..cc89e4c50 100644
--- a/compress/decompress.go
+++ b/compress/decompress.go
@@ -382,7 +382,12 @@ func (d *Decompressor) WithReadAhead(f func() error) error {
 }
 
 // DisableReadAhead - usage: `defer d.EnableReadAhead().DisableReadAhead()`. Please don't use this funcs without `defer` to avoid leak.
-func (d *Decompressor) DisableReadAhead() { _ = mmap.MadviseRandom(d.mmapHandle1) }
+func (d *Decompressor) DisableReadAhead() {
+	if d == nil || d.mmapHandle1 == nil {
+		return
+	}
+	_ = mmap.MadviseRandom(d.mmapHandle1)
+}
 func (d *Decompressor) EnableReadAhead() *Decompressor {
 	_ = mmap.MadviseSequential(d.mmapHandle1)
 	return d
diff --git a/recsplit/index.go b/recsplit/index.go
index cfea6b209..0cd92a14c 100644
--- a/recsplit/index.go
+++ b/recsplit/index.go
@@ -315,7 +315,12 @@ func (idx *Index) RewriteWithOffsets(w *bufio.Writer, m map[uint64]uint64) error
 }
 
 // DisableReadAhead - usage: `defer d.EnableReadAhead().DisableReadAhead()`. Please don't use this funcs without `defer` to avoid leak.
-func (idx *Index) DisableReadAhead() { _ = mmap.MadviseRandom(idx.mmapHandle1) }
+func (idx *Index) DisableReadAhead() {
+	if idx == nil || idx.mmapHandle1 == nil {
+		return
+	}
+	_ = mmap.MadviseRandom(idx.mmapHandle1)
+}
 func (idx *Index) EnableReadAhead() *Index {
 	_ = mmap.MadviseSequential(idx.mmapHandle1)
 	return idx
diff --git a/state/history.go b/state/history.go
index 7f6a2e2e0..9c6444e25 100644
--- a/state/history.go
+++ b/state/history.go
@@ -489,6 +489,7 @@ type historyWAL struct {
 	historyVals      *etl.Collector
 	tmpdir           string
 	autoIncrementBuf []byte
+	historyKey       []byte
 	autoIncrement    uint64
 	buffered         bool
 }
@@ -504,6 +505,7 @@ func (h *History) newWriter(tmpdir string) *historyWAL {
 	w := &historyWAL{h: h,
 		tmpdir:           tmpdir,
 		autoIncrementBuf: make([]byte, 8),
+		historyKey:       make([]byte, 0, 128),
 
 		buffered:    true,
 		historyVals: etl.NewCollector(h.historyValsTable, tmpdir, etl.NewSortableBuffer(etl.BufferOptimalSize/16)),
@@ -564,7 +566,7 @@ func (h *historyWAL) addPrevValue(key1, key2, original []byte) error {
 	*/
 
 	lk := len(key1) + len(key2)
-	historyKey := make([]byte, lk+8)
+	historyKey := h.historyKey[:lk+8]
 	copy(historyKey, key1)
 	if len(key2) > 0 {
 		copy(historyKey[len(key1):], key2)
@@ -585,6 +587,8 @@ func (h *historyWAL) addPrevValue(key1, key2, original []byte) error {
 				return err
 			}
 		}
+	} else {
+		binary.BigEndian.PutUint64(historyKey[lk:], 0)
 	}
 
 	if err := h.h.InvertedIndex.add(historyKey, historyKey[:lk]); err != nil {