diff --git a/pkg/storage/storage.go b/pkg/storage/storage.go
index c20f0603b..4d0e875cd 100644
--- a/pkg/storage/storage.go
+++ b/pkg/storage/storage.go
@@ -34,6 +34,15 @@ func (self ObjectNotFound) Error() string {
 	return "Not Found: " + self.bucket + "#" + self.path
 }
 
+type ObjectExists struct {
+	bucket string
+	key    string
+}
+
+func (self ObjectExists) Error() string {
+	return "Object exists: " + self.bucket + "#" + self.key
+}
+
 func (storage *Storage) CopyObjectToWriter(w io.Writer, bucket string, object string) (int64, error) {
 	// TODO synchronize access
 	// get object
@@ -47,8 +56,11 @@ func (storage *Storage) CopyObjectToWriter(w io.Writer, bucket string, object st
 	}
 }
 
-func (storage *Storage) StoreObject(bucket string, key string, data io.Reader) {
+func (storage *Storage) StoreObject(bucket string, key string, data io.Reader) error {
 	objectKey := bucket + ":" + key
+	if _, ok := storage.data[objectKey]; ok == true {
+		return ObjectExists{bucket: bucket, key: key}
+	}
 	var bytesBuffer bytes.Buffer
 	newObject := storedObject{}
 	if _, ok := io.Copy(&bytesBuffer, data); ok == nil {
@@ -60,6 +72,7 @@ func (storage *Storage) StoreObject(bucket string, key string, data io.Reader) {
 		newObject.data = bytesBuffer.Bytes()
 	}
 	storage.data[objectKey] = newObject
+	return nil
 }
 
 func (storage *Storage) ListObjects(bucket, prefix string, count int) []ObjectMetadata {
diff --git a/pkg/webapi/minioapi/minioapi.go b/pkg/webapi/minioapi/minioapi.go
index c45e1b139..ef99463ec 100644
--- a/pkg/webapi/minioapi/minioapi.go
+++ b/pkg/webapi/minioapi/minioapi.go
@@ -106,7 +106,12 @@ func (server *minioApi) putObjectHandler(w http.ResponseWriter, req *http.Reques
 	vars := mux.Vars(req)
 	bucket := vars["bucket"]
 	object := vars["object"]
-	server.storage.StoreObject(bucket, object, req.Body)
+	err := server.storage.StoreObject(bucket, object, req.Body)
+	if err != nil {
+		w.WriteHeader(http.StatusBadRequest)
+		w.Write([]byte(err.Error()))
+		return
+	}
 }
 
 func generateListResult(objects []mstorage.ObjectMetadata) ListResponse {