diff --git a/docs/CHANGELOG.md b/docs/CHANGELOG.md
index 2e91bada16..81d3dd4a0f 100644
--- a/docs/CHANGELOG.md
+++ b/docs/CHANGELOG.md
@@ -16,6 +16,8 @@ The following tip changes can be tested by building VictoriaMetrics components f
 ## tip
 
 
+* BUGFIX: prevent from possible panic during [background merge process](https://docs.victoriametrics.com/#storage). It may occur in rare case and was introduced at [v1.85.0](https://docs.victoriametrics.com/CHANGELOG.html#v1850) when implementing [this feature](https://github.com/VictoriaMetrics/VictoriaMetrics/issues/3337).
+
 ## [v1.88.1](https://github.com/VictoriaMetrics/VictoriaMetrics/releases/tag/v1.88.1)
 
 Released at 2023-02-27
diff --git a/lib/mergeset/table.go b/lib/mergeset/table.go
index 9fa62bc9d6..76c60cac80 100644
--- a/lib/mergeset/table.go
+++ b/lib/mergeset/table.go
@@ -1164,14 +1164,6 @@ func (tb *Table) mergeParts(pws []*partWrapper, stopCh <-chan struct{}, isFinal
 	if err != nil {
 		return fmt.Errorf("cannot atomically register the created part: %w", err)
 	}
-	tb.swapSrcWithDstParts(pws, pwNew, dstPartType)
-
-	d := time.Since(startTime)
-	if d <= 30*time.Second {
-		return nil
-	}
-
-	// Log stats for long merges.
 	dstItemsCount := uint64(0)
 	dstBlocksCount := uint64(0)
 	dstSize := uint64(0)
@@ -1183,6 +1175,15 @@ func (tb *Table) mergeParts(pws []*partWrapper, stopCh <-chan struct{}, isFinal
 		dstSize = pDst.size
 		dstPartPath = pDst.path
 	}
+
+	tb.swapSrcWithDstParts(pws, pwNew, dstPartType)
+
+	d := time.Since(startTime)
+	if d <= 30*time.Second {
+		return nil
+	}
+
+	// Log stats for long merges.
 	durationSecs := d.Seconds()
 	itemsPerSec := int(float64(srcItemsCount) / durationSecs)
 	logger.Infof("merged (%d parts, %d items, %d blocks, %d bytes) into (1 part, %d items, %d blocks, %d bytes) in %.3f seconds at %d items/sec to %q",
diff --git a/lib/storage/partition.go b/lib/storage/partition.go
index 793fa6ddf4..570b44c252 100644
--- a/lib/storage/partition.go
+++ b/lib/storage/partition.go
@@ -1376,14 +1376,7 @@ func (pt *partition) mergeParts(pws []*partWrapper, stopCh <-chan struct{}, isFi
 	if err != nil {
 		return fmt.Errorf("cannot atomically register the created part: %w", err)
 	}
-	pt.swapSrcWithDstParts(pws, pwNew, dstPartType)
 
-	d := time.Since(startTime)
-	if d <= 30*time.Second {
-		return nil
-	}
-
-	// Log stats for long merges.
 	dstRowsCount := uint64(0)
 	dstBlocksCount := uint64(0)
 	dstSize := uint64(0)
@@ -1395,6 +1388,15 @@ func (pt *partition) mergeParts(pws []*partWrapper, stopCh <-chan struct{}, isFi
 		dstSize = pDst.size
 		dstPartPath = pDst.String()
 	}
+
+	pt.swapSrcWithDstParts(pws, pwNew, dstPartType)
+
+	d := time.Since(startTime)
+	if d <= 30*time.Second {
+		return nil
+	}
+
+	// Log stats for long merges.
 	durationSecs := d.Seconds()
 	rowsPerSec := int(float64(srcRowsCount) / durationSecs)
 	logger.Infof("merged (%d parts, %d rows, %d blocks, %d bytes) into (1 part, %d rows, %d blocks, %d bytes) in %.3f seconds at %d rows/sec to %q",