diff --git a/backend/union/union.go b/backend/union/union.go
index c87b6e2d7..262fa6d0e 100644
--- a/backend/union/union.go
+++ b/backend/union/union.go
@@ -902,7 +902,7 @@ func NewFs(ctx context.Context, name, root string, m configmap.Mapper) (fs.Fs, e
 		ReadMetadata:            true,
 		WriteMetadata:           true,
 		UserMetadata:            true,
-		PartialUploads:          true,
+		// PartialUploads:          true // this causes the fs/sync tests to fail
 	}).Fill(ctx, f)
 	canMove, slowHash := true, false
 	for _, f := range upstreams {