diff --git a/daemon/containerd/image_list.go b/daemon/containerd/image_list.go
index e6bb6d17f8..e63a45a139 100644
--- a/daemon/containerd/image_list.go
+++ b/daemon/containerd/image_list.go
@@ -61,7 +61,7 @@ func (i *ImageService) Images(ctx context.Context, opts types.ImageListOptions)
 		layers    map[digest.Digest]int
 	)
 	if opts.SharedSize {
-		root = make([]*[]digest.Digest, len(imgs))
+		root = make([]*[]digest.Digest, 0, len(imgs))
 		layers = make(map[digest.Digest]int)
 	}
 	for n, img := range imgs {