diff --git a/registry/storage/driver/gcs/gcs.go b/registry/storage/driver/gcs/gcs.go
index 07f58afa..86dc87f1 100644
--- a/registry/storage/driver/gcs/gcs.go
+++ b/registry/storage/driver/gcs/gcs.go
@@ -9,6 +9,8 @@
 //
 // Note that the contents of incomplete uploads are not accessible even though
 // Stat returns their length
+//
+// +build include_gcs
 
 package gcs