diff --git a/pkg/cmd/release/create/create_test.go b/pkg/cmd/release/create/create_test.go
index f9fad4f81..8316d5baa 100644
--- a/pkg/cmd/release/create/create_test.go
+++ b/pkg/cmd/release/create/create_test.go
@@ -103,7 +103,7 @@ func Test_NewCmdCreate(t *testing.T) {
 		},
 		{
 			name:  "notes from file",
-			args:  "v1.2.3 -F" + tf.Name(),
+			args:  fmt.Sprintf(`v1.2.3 -F '%s'`, tf.Name()),
 			isTTY: true,
 			want: CreateOptions{
 				TagName:      "v1.2.3",
diff --git a/pkg/cmd/release/download/download_test.go b/pkg/cmd/release/download/download_test.go
index 8a6956bb1..cd1a5469c 100644
--- a/pkg/cmd/release/download/download_test.go
+++ b/pkg/cmd/release/download/download_test.go
@@ -6,7 +6,6 @@ import (
 	"net/http"
 	"os"
 	"path/filepath"
-	"strings"
 	"testing"
 
 	"github.com/cli/cli/internal/ghrepo"
@@ -129,9 +128,9 @@ func Test_downloadRun(t *testing.T) {
 			wantStdout: ``,
 			wantStderr: ``,
 			wantFiles: []string{
-				"./linux.tgz",
-				"./windows-32bit.zip",
-				"./windows-64bit.zip",
+				"linux.tgz",
+				"windows-32bit.zip",
+				"windows-64bit.zip",
 			},
 		},
 		{
@@ -146,8 +145,8 @@ func Test_downloadRun(t *testing.T) {
 			wantStdout: ``,
 			wantStderr: ``,
 			wantFiles: []string{
-				"./tmp/assets/windows-32bit.zip",
-				"./tmp/assets/windows-64bit.zip",
+				"tmp/assets/windows-32bit.zip",
+				"tmp/assets/windows-64bit.zip",
 			},
 		},
 		{
@@ -221,7 +220,11 @@ func listFiles(dir string) ([]string, error) {
 	var files []string
 	err := filepath.Walk(dir, func(p string, f os.FileInfo, err error) error {
 		if !f.IsDir() {
-			files = append(files, "."+strings.TrimPrefix(p, dir))
+			rp, err := filepath.Rel(dir, p)
+			if err != nil {
+				return err
+			}
+			files = append(files, filepath.ToSlash(rp))
 		}
 		return err
 	})
diff --git a/pkg/cmd/release/shared/upload.go b/pkg/cmd/release/shared/upload.go
index bdb0c837a..ef5ff4890 100644
--- a/pkg/cmd/release/shared/upload.go
+++ b/pkg/cmd/release/shared/upload.go
@@ -56,14 +56,13 @@ func AssetsFromArgs(args []string) (assets []*AssetForUpload, err error) {
 }
 
 func typeForFilename(fn string) string {
-	fn = strings.ToLower(fn)
-	if strings.HasSuffix(fn, ".tar.gz") {
-		return "application/x-gtar"
-	}
-
-	ext := path.Ext(fn)
+	ext := fileExt(fn)
 	switch ext {
-	case ".tgz":
+	case "zip":
+		return "application/zip"
+	case "js":
+		return "application/javascript"
+	case ".tgz", ".tar.gz":
 		return "application/x-gtar"
 	case ".bz2":
 		return "application/x-bzip2"
@@ -71,6 +70,8 @@ func typeForFilename(fn string) string {
 		return "application/x-apple-diskimage"
 	case ".rpm":
 		return "application/x-rpm"
+	case ".deb":
+		return "application/x-debian-package"
 	}
 
 	t := mime.TypeByExtension(ext)
@@ -80,6 +81,14 @@ func typeForFilename(fn string) string {
 	return t
 }
 
+func fileExt(fn string) string {
+	fn = strings.ToLower(fn)
+	if strings.HasSuffix(fn, ".tar.gz") {
+		return ".tar.gz"
+	}
+	return path.Ext(fn)
+}
+
 func ConcurrentUpload(httpClient *http.Client, uploadURL string, numWorkers int, assets []*AssetForUpload) error {
 	if numWorkers == 0 {
 		return errors.New("the number of concurrent workers needs to be greater than 0")