diff --git a/test/s3/multipart/aws_upload.go b/test/s3/multipart/aws_upload.go
index 24a186625..8c15cf6ed 100644
--- a/test/s3/multipart/aws_upload.go
+++ b/test/s3/multipart/aws_upload.go
@@ -6,6 +6,7 @@ import (
 	"bytes"
 	"flag"
 	"fmt"
+	"net/http"
 	"os"
 
 	"github.com/aws/aws-sdk-go/aws"
@@ -48,8 +49,7 @@ func main() {
 	fileInfo, _ := file.Stat()
 	size := fileInfo.Size()
 	buffer := make([]byte, size)
-	// fileType := http.DetectContentType(buffer)
-	fileType := "application/octet-stream"
+	fileType := http.DetectContentType(buffer)
 	file.Read(buffer)
 
 	path := "/media/" + file.Name()
diff --git a/weed/command/filer_copy.go b/weed/command/filer_copy.go
index 03680e81b..88148acc5 100644
--- a/weed/command/filer_copy.go
+++ b/weed/command/filer_copy.go
@@ -5,6 +5,7 @@ import (
 	"fmt"
 	"io"
 	"io/ioutil"
+	"net/http"
 	"net/url"
 	"os"
 	"path/filepath"
@@ -277,8 +278,7 @@ func (worker *FileCopyWorker) uploadFileAsOne(task FileCopyTask, f *os.File) err
 
 	// upload the file content
 	fileName := filepath.Base(f.Name())
-	// mimeType := detectMimeType(f)
-	mimeType := "application/octet-stream"
+	mimeType := detectMimeType(f)
 	data, err := ioutil.ReadAll(f)
 	if err != nil {
 		return err
@@ -365,8 +365,7 @@ func (worker *FileCopyWorker) uploadFileAsOne(task FileCopyTask, f *os.File) err
 func (worker *FileCopyWorker) uploadFileInChunks(task FileCopyTask, f *os.File, chunkCount int, chunkSize int64) error {
 
 	fileName := filepath.Base(f.Name())
-	// mimeType := detectMimeType(f)
-	mimeType := "application/octet-stream"
+	mimeType := detectMimeType(f)
 
 	chunksChan := make(chan *filer_pb.FileChunk, chunkCount)
 
@@ -488,7 +487,7 @@ func (worker *FileCopyWorker) uploadFileInChunks(task FileCopyTask, f *os.File,
 func detectMimeType(f *os.File) string {
 	head := make([]byte, 512)
 	f.Seek(0, io.SeekStart)
-	_, err := f.Read(head)
+	n, err := f.Read(head)
 	if err == io.EOF {
 		return ""
 	}
@@ -497,8 +496,7 @@ func detectMimeType(f *os.File) string {
 		return ""
 	}
 	f.Seek(0, io.SeekStart)
-	// mimeType := http.DetectContentType(head[:n])
-	mimeType := "application/octet-stream"
+	mimeType := http.DetectContentType(head[:n])
 	if mimeType == "application/octet-stream" {
 		return ""
 	}
diff --git a/weed/filesys/filehandle.go b/weed/filesys/filehandle.go
index 61ebbfc09..687588788 100644
--- a/weed/filesys/filehandle.go
+++ b/weed/filesys/filehandle.go
@@ -5,6 +5,7 @@ import (
 	"fmt"
 	"io"
 	"math"
+	"net/http"
 	"os"
 	"sync"
 	"time"
@@ -153,8 +154,7 @@ func (fh *FileHandle) Write(ctx context.Context, req *fuse.WriteRequest, resp *f
 
 	if req.Offset == 0 {
 		// detect mime type
-		// fh.contentType = http.DetectContentType(data)
-		fh.contentType = "application/octet-stream"
+		fh.contentType = http.DetectContentType(data)
 		fh.f.dirtyMetadata = true
 	}
 
diff --git a/weed/operation/upload_content.go b/weed/operation/upload_content.go
index f783da440..e9002d09d 100644
--- a/weed/operation/upload_content.go
+++ b/weed/operation/upload_content.go
@@ -102,8 +102,7 @@ func doUploadData(uploadUrl string, filename string, cipher bool, data []byte, i
 	shouldGzipNow := false
 	if !isInputCompressed {
 		if mtype == "" {
-			// mtype = http.DetectContentType(data)
-			mtype = "application/octet-stream"
+			mtype = http.DetectContentType(data)
 			// println("detect1 mimetype to", mtype)
 			if mtype == "application/octet-stream" {
 				mtype = ""
diff --git a/weed/server/filer_server_handlers_write_cipher.go b/weed/server/filer_server_handlers_write_cipher.go
index 175a880bf..60082a8d4 100644
--- a/weed/server/filer_server_handlers_write_cipher.go
+++ b/weed/server/filer_server_handlers_write_cipher.go
@@ -37,8 +37,7 @@ func (fs *FilerServer) encrypt(ctx context.Context, w http.ResponseWriter, r *ht
 		uncompressedData = pu.UncompressedData
 	}
 	if pu.MimeType == "" {
-		// pu.MimeType = http.DetectContentType(uncompressedData)
-		pu.MimeType = "application/octet-stream"
+		pu.MimeType = http.DetectContentType(uncompressedData)
 		// println("detect2 mimetype to", pu.MimeType)
 	}
 
diff --git a/weed/storage/needle/needle_parse_upload.go b/weed/storage/needle/needle_parse_upload.go
index da4dd0ee9..4d244046e 100644
--- a/weed/storage/needle/needle_parse_upload.go
+++ b/weed/storage/needle/needle_parse_upload.go
@@ -66,8 +66,7 @@ func ParseUpload(r *http.Request, sizeLimit int64) (pu *ParsedUpload, e error) {
 		ext := filepath.Base(pu.FileName)
 		mimeType := pu.MimeType
 		if mimeType == "" {
-			// mimeType = http.DetectContentType(pu.Data)
-			mimeType = "application/octet-stream"
+			mimeType = http.DetectContentType(pu.Data)
 		}
 		// println("detected mimetype to", pu.MimeType)
 		if mimeType == "application/octet-stream" {