diff --git a/core/images/archive/exporter.go b/core/images/archive/exporter.go
index 1377336a9..3d98daea1 100644
--- a/core/images/archive/exporter.go
+++ b/core/images/archive/exporter.go
@@ -466,6 +466,7 @@ func ociIndexRecord(manifests []ocispec.Descriptor) tarRecord {
 		Versioned: ocispecs.Versioned{
 			SchemaVersion: 2,
 		},
+		MediaType: ocispec.MediaTypeImageIndex,
 		Manifests: manifests,
 	}