diff --git a/pkg/api/merge.go b/pkg/api/merge.go
index ec18cc11..63b1aa35 100644
--- a/pkg/api/merge.go
+++ b/pkg/api/merge.go
@@ -116,7 +116,7 @@ func Merge(destFile string, inFiles []string, w io.Writer, conf *model.Configura
 	}
 
 	if conf.CreateBookmarks {
-		if err := pdfcpu.EnsureOutlines(ctxDest, filepath.Base(destFile)); err != nil {
+		if err := pdfcpu.EnsureOutlines(ctxDest, filepath.Base(destFile), conf.Cmd == model.MERGEAPPEND); err != nil {
 			return err
 		}
 	}
@@ -190,11 +190,11 @@ func MergeAppendFile(inFiles []string, outFile string, conf *model.Configuration
 
 	defer func() {
 		if err != nil {
-			if err = f.Close(); err != nil {
+			if err1 := f.Close(); err1 != nil {
 				return
 			}
 			if overWrite {
-				err = os.Remove(tmpFile)
+				os.Remove(tmpFile)
 			}
 			return
 		}
@@ -206,5 +206,6 @@ func MergeAppendFile(inFiles []string, outFile string, conf *model.Configuration
 		}
 	}()
 
-	return Merge(destFile, inFiles, f, conf)
+	err = Merge(destFile, inFiles, f, conf)
+	return err
 }
diff --git a/pkg/api/test/merge_test.go b/pkg/api/test/merge_test.go
index b339295f..34ecd14a 100644
--- a/pkg/api/test/merge_test.go
+++ b/pkg/api/test/merge_test.go
@@ -63,6 +63,12 @@ func TestMergeAppendNew(t *testing.T) {
 	if err := api.MergeAppendFile(inFiles, outFile, nil); err != nil {
 		t.Fatalf("%s: %v\n", msg, err)
 	}
+
+	anotherFile := filepath.Join(inDir, "testRot.pdf")
+	err := api.MergeAppendFile([]string{anotherFile}, outFile, nil)
+	if err != nil {
+		t.Fatalf("%s: %v\n", msg, err)
+	}
 }
 
 func TestMergeToBufNew(t *testing.T) {
@@ -92,6 +98,7 @@ func TestMergeRaw(t *testing.T) {
 		filepath.Join(inDir, "Acroforms2.pdf"),
 		filepath.Join(inDir, "adobe_errata.pdf"),
 	}
+	outFile := filepath.Join(outDir, "test.pdf")
 
 	var rsc []io.ReadSeeker = make([]io.ReadSeeker, 2)
 
@@ -104,15 +111,12 @@ func TestMergeRaw(t *testing.T) {
 
 	f1, err := os.Open(inFiles[1])
 	if err != nil {
-		t.Fatalf("%s: open file1: %v\n", msg, err)
+		t.Fatalf("%s: open file2: %v\n", msg, err)
 	}
 	defer f1.Close()
 	rsc[1] = f1
 
-	outFile := filepath.Join(outDir, "test.pdf")
-
 	buf := &bytes.Buffer{}
-
 	if err := api.MergeRaw(rsc, buf, nil); err != nil {
 		t.Fatalf("%s: merge: %v\n", msg, err)
 	}
diff --git a/pkg/pdfcpu/merge.go b/pkg/pdfcpu/merge.go
index e203cae5..1211c14a 100644
--- a/pkg/pdfcpu/merge.go
+++ b/pkg/pdfcpu/merge.go
@@ -24,7 +24,7 @@ import (
 	"github.com/pdfcpu/pdfcpu/pkg/pdfcpu/types"
 )
 
-func EnsureOutlines(ctx *model.Context, fName string) error {
+func EnsureOutlines(ctx *model.Context, fName string, append bool) error {
 
 	rootDict, err := ctx.Catalog()
 	if err != nil {
@@ -51,6 +51,9 @@ func EnsureOutlines(ctx *model.Context, fName string) error {
 	outlinesDict["Count"] = types.Integer(total + visible)
 
 	if obj, ok := rootDict.Find("Outlines"); ok {
+		if append {
+			return nil
+		}
 		d, err := ctx.DereferenceDict(obj)
 		if err != nil {
 			return err