diff --git a/.github/workflows/golangci-lint.yml b/.github/workflows/golangci-lint.yml
index 6b9abea..66f33b6 100644
--- a/.github/workflows/golangci-lint.yml
+++ b/.github/workflows/golangci-lint.yml
@@ -12,7 +12,7 @@ jobs:
     runs-on: ubuntu-latest
     strategy:
       matrix:
-        go-version: [ '1.20' ]
+        go-version: [ '1.20', '1.21' ]
     steps:
       - uses: actions/checkout@v3
       - name: Setup Go
@@ -23,4 +23,4 @@ jobs:
       - name: golangci-lint
         uses: golangci/golangci-lint-action@v3
         with:
-          version: v1.53.3
+          version: v1.54.0
diff --git a/.github/workflows/unit.yml b/.github/workflows/unit.yml
index c0fe53a..a3266eb 100644
--- a/.github/workflows/unit.yml
+++ b/.github/workflows/unit.yml
@@ -11,7 +11,7 @@ jobs:
     runs-on: ubuntu-latest
     strategy:
       matrix:
-        go-version: [ '1.20' ]
+        go-version: [ '1.20', '1.21' ]
     steps:
       - uses: actions/checkout@v3
       - name: Setup Go
diff --git a/packer.go b/packer.go
index 8136249..2771d34 100644
--- a/packer.go
+++ b/packer.go
@@ -72,10 +72,11 @@ func (p *Packer) preferredSort(boxes boxSlice, items itemSlice) boxSlice {
 func (p *Packer) packToBox(b *Box, items []*Item) []*Item {
 	var fitted bool
 
-	unpacked := make([]*Item, 0, len(items))
+	cntItems := len(items)
+	unpacked := make([]*Item, 0, cntItems)
 	pv := Pivot{}
 
-	if b.items == nil && b.PutItem(items[0], pv) {
+	if b.items == nil && cntItems > 0 && b.PutItem(items[0], pv) {
 		items = items[1:]
 	}
 
diff --git a/packer_test.go b/packer_test.go
index eac813b..916a656 100644
--- a/packer_test.go
+++ b/packer_test.go
@@ -79,6 +79,32 @@ func TestBoxPackerSuite(t *testing.T) {
 	suite.Run(t, new(PackerSuit))
 }
 
+func (s *PackerSuit) TestEmptyBoxes() {
+	t := s.T()
+	t.Parallel()
+
+	packer := boxpacker3.NewPacker()
+
+	packResult := packer.Pack(nil, nil)
+	require.NotNil(t, packResult)
+	require.Len(t, packResult.Boxes, 0)
+	require.Len(t, packResult.UnfitItems, 0)
+}
+
+func (s *PackerSuit) TestEmptyItems() {
+	t := s.T()
+	t.Parallel()
+
+	packer := boxpacker3.NewPacker()
+
+	boxes := NewDefaultBoxList()
+
+	packResult := packer.Pack(boxes, nil)
+	require.NotNil(t, packResult)
+	require.Len(t, packResult.Boxes, len(boxes))
+	require.Len(t, packResult.UnfitItems, 0)
+}
+
 func (s *PackerSuit) TestMinBox() {
 	t := s.T()
 	t.Parallel()