diff --git a/cors_test.go b/cors_test.go
index fd56f80..2bb636f 100644
--- a/cors_test.go
+++ b/cors_test.go
@@ -21,7 +21,7 @@ func TestCORS(t *testing.T) {
 			},
 			Code: http.StatusOK,
 			ResHeader: map[string]string{
-				"Access-Control-Allow-Headers": "Origin, X-Requested-With, Content-Type, Upload-Length, Upload-Offset, Tus-Resumable, Upload-Metadata, Upload-Defer-Length",
+				"Access-Control-Allow-Headers": "Origin, X-Requested-With, Content-Type, Upload-Length, Upload-Offset, Tus-Resumable, Upload-Metadata, Upload-Defer-Length, Upload-Concat",
 				"Access-Control-Allow-Methods": "POST, GET, HEAD, PATCH, DELETE, OPTIONS",
 				"Access-Control-Max-Age":       "86400",
 				"Access-Control-Allow-Origin":  "tus.io",
@@ -42,7 +42,7 @@ func TestCORS(t *testing.T) {
 			},
 			Code: http.StatusMethodNotAllowed,
 			ResHeader: map[string]string{
-				"Access-Control-Expose-Headers": "Upload-Offset, Location, Upload-Length, Tus-Version, Tus-Resumable, Tus-Max-Size, Tus-Extension, Upload-Metadata, Upload-Defer-Length",
+				"Access-Control-Expose-Headers": "Upload-Offset, Location, Upload-Length, Tus-Version, Tus-Resumable, Tus-Max-Size, Tus-Extension, Upload-Metadata, Upload-Defer-Length, Upload-Concat",
 				"Access-Control-Allow-Origin":   "tus.io",
 			},
 		}).Run(handler, t)
diff --git a/unrouted_handler.go b/unrouted_handler.go
index 20e70ff..4115b8e 100644
--- a/unrouted_handler.go
+++ b/unrouted_handler.go
@@ -174,12 +174,12 @@ func (handler *UnroutedHandler) Middleware(h http.Handler) http.Handler {
 			if r.Method == "OPTIONS" {
 				// Preflight request
 				header.Add("Access-Control-Allow-Methods", "POST, GET, HEAD, PATCH, DELETE, OPTIONS")
-				header.Add("Access-Control-Allow-Headers", "Origin, X-Requested-With, Content-Type, Upload-Length, Upload-Offset, Tus-Resumable, Upload-Metadata, Upload-Defer-Length")
+				header.Add("Access-Control-Allow-Headers", "Origin, X-Requested-With, Content-Type, Upload-Length, Upload-Offset, Tus-Resumable, Upload-Metadata, Upload-Defer-Length, Upload-Concat")
 				header.Set("Access-Control-Max-Age", "86400")
 
 			} else {
 				// Actual request
-				header.Add("Access-Control-Expose-Headers", "Upload-Offset, Location, Upload-Length, Tus-Version, Tus-Resumable, Tus-Max-Size, Tus-Extension, Upload-Metadata, Upload-Defer-Length")
+				header.Add("Access-Control-Expose-Headers", "Upload-Offset, Location, Upload-Length, Tus-Version, Tus-Resumable, Tus-Max-Size, Tus-Extension, Upload-Metadata, Upload-Defer-Length, Upload-Concat")
 			}
 		}