diff --git a/weed/s3api/filer_multipart.go b/weed/s3api/filer_multipart.go
index fca1a0aa4..a7d4b95a7 100644
--- a/weed/s3api/filer_multipart.go
+++ b/weed/s3api/filer_multipart.go
@@ -82,9 +82,13 @@ func (s3a *S3ApiServer) completeMultipartUpload(input *s3.CompleteMultipartUploa
 
 	var finalParts []*filer_pb.FileChunk
 	var offset int64
+	var mime string
 
 	for _, entry := range entries {
 		if strings.HasSuffix(entry.Name, ".part") && !entry.IsDirectory {
+			if entry.Name == "0001.part" && entry.Attributes.Mime != "" {
+				mime = entry.Attributes.Mime
+			}
 			for _, chunk := range entry.Chunks {
 				p := &filer_pb.FileChunk{
 					FileId:    chunk.GetFileIdString(),
@@ -126,6 +130,8 @@ func (s3a *S3ApiServer) completeMultipartUpload(input *s3.CompleteMultipartUploa
 		}
 		if pentry.Attributes.Mime != "" {
 			entry.Attributes.Mime = pentry.Attributes.Mime
+		} else if mime != "" {
+			entry.Attributes.Mime = mime
 		}
 	})
 
diff --git a/weed/s3api/s3api_object_handlers.go b/weed/s3api/s3api_object_handlers.go
index 0b7e8043f..16f5f34f3 100644
--- a/weed/s3api/s3api_object_handlers.go
+++ b/weed/s3api/s3api_object_handlers.go
@@ -1,6 +1,7 @@
 package s3api
 
 import (
+	"bytes"
 	"crypto/md5"
 	"encoding/json"
 	"encoding/xml"
@@ -36,6 +37,13 @@ func init() {
 	}}
 }
 
+func mimeDetect(r *http.Request, dataReader io.Reader) io.ReadCloser {
+	mimeBuffer := make([]byte, 512)
+	dataReader.Read(mimeBuffer)
+	r.Header.Set("Content-Type", http.DetectContentType(mimeBuffer))
+	return io.NopCloser(io.MultiReader(bytes.NewReader(mimeBuffer), dataReader))
+}
+
 func (s3a *S3ApiServer) PutObjectHandler(w http.ResponseWriter, r *http.Request) {
 
 	// http://docs.aws.amazon.com/AmazonS3/latest/dev/UploadingObjects.html
@@ -95,6 +103,10 @@ func (s3a *S3ApiServer) PutObjectHandler(w http.ResponseWriter, r *http.Request)
 	} else {
 		uploadUrl := fmt.Sprintf("http://%s%s/%s%s", s3a.option.Filer.ToHttpAddress(), s3a.option.BucketsPath, bucket, urlPathEscape(object))
 
+		if r.Header.Get("Content-Type") == "" {
+			dataReader = mimeDetect(r, dataReader)
+		}
+
 		etag, errCode := s3a.putToFiler(r, uploadUrl, dataReader)
 
 		if errCode != s3err.ErrNone {
diff --git a/weed/s3api/s3api_object_multipart_handlers.go b/weed/s3api/s3api_object_multipart_handlers.go
index ab72b8437..486161dfb 100644
--- a/weed/s3api/s3api_object_multipart_handlers.go
+++ b/weed/s3api/s3api_object_multipart_handlers.go
@@ -217,8 +217,11 @@ func (s3a *S3ApiServer) PutObjectPartHandler(w http.ResponseWriter, r *http.Requ
 	uploadUrl := fmt.Sprintf("http://%s%s/%s/%04d.part?collection=%s",
 		s3a.option.Filer.ToHttpAddress(), s3a.genUploadsFolder(bucket), uploadID, partID, bucket)
 
-	etag, errCode := s3a.putToFiler(r, uploadUrl, dataReader)
+	if partID == 1 && r.Header.Get("Content-Type") == "" {
+		dataReader = mimeDetect(r, dataReader)
+	}
 
+	etag, errCode := s3a.putToFiler(r, uploadUrl, dataReader)
 	if errCode != s3err.ErrNone {
 		s3err.WriteErrorResponse(w, errCode, r)
 		return