diff --git a/lib/mergeset/table.go b/lib/mergeset/table.go
index ea81ebd7c..40e66f8be 100644
--- a/lib/mergeset/table.go
+++ b/lib/mergeset/table.go
@@ -565,7 +565,7 @@ func (tb *Table) mergeRawItemsBlocks(blocksToMerge []*inmemoryBlock) {
 
 func (tb *Table) mergeInmemoryBlocks(blocksToMerge []*inmemoryBlock) *partWrapper {
 	// Convert blocksToMerge into inmemoryPart's
-	pws := make([]*partWrapper, 0, len(blocksToMerge))
+	mps := make([]*inmemoryPart, 0, len(blocksToMerge))
 	for _, ib := range blocksToMerge {
 		if len(ib.items) == 0 {
 			continue
@@ -573,24 +573,25 @@ func (tb *Table) mergeInmemoryBlocks(blocksToMerge []*inmemoryBlock) *partWrappe
 		mp := getInmemoryPart()
 		mp.Init(ib)
 		putInmemoryBlock(ib)
+		mps = append(mps, mp)
+	}
+	if len(mps) == 0 {
+		return nil
+	}
+	if len(mps) == 1 {
+		// Nothing to merge. Just return a single inmemory part.
+		mp := mps[0]
 		p := mp.NewPart()
-		pw := &partWrapper{
+		return &partWrapper{
 			p:        p,
 			mp:       mp,
 			refCount: 1,
 		}
-		pws = append(pws, pw)
-	}
-	if len(pws) == 0 {
-		return nil
-	}
-	if len(pws) == 1 {
-		return pws[0]
 	}
 	defer func() {
 		// Return source inmemoryParts to pool.
-		for _, pw := range pws {
-			putInmemoryPart(pw.mp)
+		for _, mp := range mps {
+			putInmemoryPart(mp)
 		}
 	}()
 
@@ -599,10 +600,10 @@ func (tb *Table) mergeInmemoryBlocks(blocksToMerge []*inmemoryBlock) *partWrappe
 	defer atomic.AddUint64(&tb.activeMerges, ^uint64(0))
 
 	// Prepare blockStreamReaders for source parts.
-	bsrs := make([]*blockStreamReader, 0, len(pws))
-	for _, pw := range pws {
+	bsrs := make([]*blockStreamReader, 0, len(mps))
+	for _, mp := range mps {
 		bsr := getBlockStreamReader()
-		bsr.InitFromInmemoryPart(pw.mp)
+		bsr.InitFromInmemoryPart(mp)
 		bsrs = append(bsrs, bsr)
 	}