diff --git a/server/common/proxy.go b/server/common/proxy.go
index 8156dc885ef..a4f04abfe2c 100644
--- a/server/common/proxy.go
+++ b/server/common/proxy.go
@@ -17,6 +17,10 @@ func Proxy(w http.ResponseWriter, r *http.Request, link *model.Link, file model.
 	if link.MFile != nil {
 		defer link.MFile.Close()
 		attachFileName(w, file)
+		contentType := link.Header.Get("Content-Type")
+		if contentType != "" {
+			w.Header().Add("Content-Type", contentType)
+		}
 		http.ServeContent(w, r, file.GetName(), file.ModTime(), link.MFile)
 		return nil
 	} else if link.RangeReadCloser != nil {