diff --git a/spec/spec.go b/spec/spec.go
index 330069d..8665f6f 100644
--- a/spec/spec.go
+++ b/spec/spec.go
@@ -3,10 +3,14 @@ package spec
 const (
 	// MediaTypeLayerEnc is MIME type used for encrypted layers.
 	MediaTypeLayerEnc = "application/vnd.oci.image.layer.v1.tar+encrypted"
-	// MediaTypeLayerGzipEnc is MIME type used for encrypted compressed layers.
+	// MediaTypeLayerGzipEnc is MIME type used for encrypted gzip-compressed layers.
 	MediaTypeLayerGzipEnc = "application/vnd.oci.image.layer.v1.tar+gzip+encrypted"
+	// MediaTypeLayerZstdEnc is MIME type used for encrypted zstd-compressed layers.
+	MediaTypeLayerZstdEnc = "application/vnd.oci.image.layer.v1.tar+zstd+encrypted"
 	// MediaTypeLayerNonDistributableEnc is MIME type used for non distributable encrypted layers.
 	MediaTypeLayerNonDistributableEnc = "application/vnd.oci.image.layer.nondistributable.v1.tar+encrypted"
-	// MediaTypeLayerGzipEnc is MIME type used for non distributable encrypted compressed layers.
+	// MediaTypeLayerGzipEnc is MIME type used for non distributable encrypted gzip-compressed layers.
 	MediaTypeLayerNonDistributableGzipEnc = "application/vnd.oci.image.layer.nondistributable.v1.tar+gzip+encrypted"
+	// MediaTypeLayerZstdEnc is MIME type used for non distributable encrypted zstd-compressed layers.
+	MediaTypeLayerNonDistributableZsdtEnc = "application/vnd.oci.image.layer.nondistributable.v1.tar+zstd+encrypted"
 )