diff --git a/pkg/blobserver/handlers/upload.go b/pkg/blobserver/handlers/upload.go
index b0bb6d72c..9f6527d97 100644
--- a/pkg/blobserver/handlers/upload.go
+++ b/pkg/blobserver/handlers/upload.go
@@ -177,7 +177,7 @@ func handleMultiPartUpload(rw http.ResponseWriter, req *http.Request, blobReceiv
 
 	receivedBlobs := make([]blob.SizedRef, 0, 10)
 
-	multipart, err := req.MultipartReader()
+	multipart, err := httputil.MultipartReader(req)
 	if multipart == nil {
 		httputil.BadRequestError(rw, fmt.Sprintf(
 			"Expected multipart/form-data POST request; %v", err))
diff --git a/pkg/httputil/multipart.go b/pkg/httputil/multipart.go
new file mode 100644
index 000000000..94431f385
--- /dev/null
+++ b/pkg/httputil/multipart.go
@@ -0,0 +1,59 @@
+/*
+Copyright 2015 The Camlistore Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+     http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+// This file provides an alternative function to the stdlib's (r
+// *http.Request).MultiMultipartReader(), because we want to obtain a multipart
+// Reader from the vendored "future/mime/multipart" instead of from the stdlib's
+// "mime/multipart".
+
+package httputil
+
+import (
+	"future/mime/multipart" // vendored copy of Go tip "mime/multipart"
+	"mime"
+	"net/http"
+)
+
+// TODO(mpl, bradfitz): remove that whole file once we depend on Go 1.6
+// See https://camlistore.org/issue/644
+
+// MultipartReader returns a MIME multipart reader if this is a
+// multipart/form-data POST request, else returns nil and an error.
+// Use this function instead of ParseMultipartForm to
+// process the request body as a stream.
+func MultipartReader(r *http.Request) (*multipart.Reader, error) {
+	_, err := r.MultipartReader()
+	if err != nil {
+		return nil, err
+	}
+	return multipartReader(r)
+}
+
+func multipartReader(r *http.Request) (*multipart.Reader, error) {
+	v := r.Header.Get("Content-Type")
+	if v == "" {
+		return nil, http.ErrNotMultipart
+	}
+	d, params, err := mime.ParseMediaType(v)
+	if err != nil || d != "multipart/form-data" {
+		return nil, http.ErrNotMultipart
+	}
+	boundary, ok := params["boundary"]
+	if !ok {
+		return nil, http.ErrMissingBoundary
+	}
+	return multipart.NewReader(r.Body, boundary), nil
+}
diff --git a/pkg/server/uploadhelper.go b/pkg/server/uploadhelper.go
index a9fec2e3c..2d76752c8 100644
--- a/pkg/server/uploadhelper.go
+++ b/pkg/server/uploadhelper.go
@@ -46,7 +46,7 @@ func (ui *UIHandler) serveUploadHelper(rw http.ResponseWriter, req *http.Request
 		return
 	}
 
-	mr, err := req.MultipartReader()
+	mr, err := httputil.MultipartReader(req)
 	if err != nil {
 		httputil.ServeJSONError(rw, httputil.ServerError("reading body: "+err.Error()))
 		return