diff --git a/conformance/03_discovery_test.go b/conformance/03_discovery_test.go
index 61a86caf..67b2b395 100644
--- a/conformance/03_discovery_test.go
+++ b/conformance/03_discovery_test.go
@@ -145,6 +145,18 @@ var test03ContentDiscovery = func() {
 					BeNumerically("<", 300)))
 				Expect(resp.Header().Get("OCI-Subject")).To(Equal(manifests[4].Digest))
 
+				// Populate registry with test index manifest
+				req = client.NewRequest(reggie.PUT, "/v2/<name>/manifests/<reference>",
+					reggie.WithReference(refsIndexArtifactDigest)).
+					SetHeader("Content-Type", "application/vnd.oci.image.index.v1+json").
+					SetBody(refsIndexArtifactContent)
+				resp, err = client.Do(req)
+				Expect(err).To(BeNil())
+				Expect(resp.StatusCode()).To(SatisfyAll(
+					BeNumerically(">=", 200),
+					BeNumerically("<", 300)))
+				Expect(resp.Header().Get("OCI-Subject")).To(Equal(manifests[4].Digest))
+
 				// Populate registry with test blob
 				req = client.NewRequest(reggie.POST, "/v2/<name>/blobs/uploads/")
 				resp, err = client.Do(req)
@@ -300,7 +312,7 @@ var test03ContentDiscovery = func() {
 				var index index
 				err = json.Unmarshal(resp.Body(), &index)
 				Expect(err).To(BeNil())
-				Expect(len(index.Manifests)).To(Equal(4))
+				Expect(len(index.Manifests)).To(Equal(5))
 				Expect(index.Manifests[0].Digest).ToNot(Equal(index.Manifests[1].Digest))
 			})
 
@@ -325,7 +337,7 @@ var test03ContentDiscovery = func() {
 					Expect(len(index.Manifests)).To(Equal(2))
 					Expect(resp.Header().Get("OCI-Filters-Applied")).To(Equal(artifactTypeFilter))
 				} else {
-					Expect(len(index.Manifests)).To(Equal(4))
+					Expect(len(index.Manifests)).To(Equal(5))
 					Warn("filtering by artifact-type is not implemented")
 				}
 			})
@@ -414,6 +426,9 @@ var test03ContentDiscovery = func() {
 
 				if deleteManifestBeforeBlobs {
 					req := client.NewRequest(reggie.DELETE, "/v2/<name>/manifests/<reference>",
+						reggie.WithReference(refsIndexArtifactDigest))
+					deleteReq(req)
+					req = client.NewRequest(reggie.DELETE, "/v2/<name>/manifests/<reference>",
 						reggie.WithReference(refsManifestAConfigArtifactDigest))
 					deleteReq(req)
 					req = client.NewRequest(reggie.DELETE, "/v2/<name>/manifests/<reference>",
@@ -445,6 +460,9 @@ var test03ContentDiscovery = func() {
 
 				if !deleteManifestBeforeBlobs {
 					// Delete manifest created in setup
+					req = client.NewRequest(reggie.DELETE, "/v2/<name>/manifests/<reference>",
+						reggie.WithReference(refsIndexArtifactDigest))
+					deleteReq(req)
 					req = client.NewRequest(reggie.DELETE, "/v2/<name>/manifests/<reference>",
 						reggie.WithReference(refsManifestAConfigArtifactDigest))
 					deleteReq(req)
diff --git a/conformance/image.go b/conformance/image.go
index 75c1672b..23ac56ad 100644
--- a/conformance/image.go
+++ b/conformance/image.go
@@ -29,6 +29,9 @@ type manifest struct {
 
 	// Subject is an optional link from the image manifest to another manifest forming an association between the image manifest and the other manifest.
 	Subject *descriptor `json:"subject,omitempty"`
+
+	// Annotations contains arbitrary metadata for the image index.
+	Annotations map[string]string `json:"annotations,omitempty"`
 }
 
 // descriptor describes the disposition of targeted content.
@@ -90,9 +93,15 @@ type index struct {
 	// MediaType specifies the type of this document data structure e.g. `application/vnd.oci.image.index.v1+json`
 	MediaType string `json:"mediaType,omitempty"`
 
+	// ArtifactType specifies the IANA media type of artifact when the manifest is used for an artifact.
+	ArtifactType string `json:"artifactType,omitempty"`
+
 	// Manifests references platform specific manifests.
 	Manifests []descriptor `json:"manifests"`
 
+	// Subject is an optional link from the image manifest to another manifest forming an association between the image manifest and the other manifest.
+	Subject *descriptor `json:"subject,omitempty"`
+
 	// Annotations contains arbitrary metadata for the image index.
 	Annotations map[string]string `json:"annotations,omitempty"`
 }
diff --git a/conformance/setup.go b/conformance/setup.go
index 11ef3278..5f3058ff 100644
--- a/conformance/setup.go
+++ b/conformance/setup.go
@@ -112,6 +112,7 @@ var (
 	testRefBlobADigest                 string
 	testRefArtifactTypeA               string
 	testRefArtifactTypeB               string
+	testRefArtifactTypeIndex           string
 	testRefBlobB                       []byte
 	testRefBlobBLength                 string
 	testRefBlobBDigest                 string
@@ -144,6 +145,8 @@ var (
 	refsManifestBConfigArtifactDigest  string
 	refsManifestBLayerArtifactContent  []byte
 	refsManifestBLayerArtifactDigest   string
+	refsIndexArtifactContent           []byte
+	refsIndexArtifactDigest            string
 	reportJUnitFilename                string
 	reportHTMLFilename                 string
 	httpWriter                         *httpDebugWriter
@@ -435,6 +438,35 @@ func init() {
 
 	refsManifestBLayerArtifactDigest = godigest.FromBytes(refsManifestBLayerArtifactContent).String()
 
+	testRefArtifactTypeIndex = "application/vnd.food.stand"
+	refsIndexArtifact := index{
+		SchemaVersion: 2,
+		MediaType:     "application/vnd.oci.image.index.v1+json",
+		ArtifactType:  testRefArtifactTypeIndex,
+		Manifests: []descriptor{
+			{
+				MediaType: "application/vnd.oci.image.manifest.v1+json",
+				Size:      int64(len(refsManifestAConfigArtifactContent)),
+				Digest:    godigest.FromBytes(refsManifestAConfigArtifactContent),
+			},
+			{
+				MediaType: "application/vnd.oci.image.manifest.v1+json",
+				Size:      int64(len(refsManifestALayerArtifactContent)),
+				Digest:    godigest.FromBytes(refsManifestALayerArtifactContent),
+			},
+		},
+		Subject: &descriptor{
+			MediaType: "application/vnd.oci.image.manifest.v1+json",
+			Size:      int64(len(manifests[4].Content)),
+			Digest:    godigest.FromBytes(manifests[4].Content),
+		},
+	}
+	refsIndexArtifactContent, err = json.MarshalIndent(&refsIndexArtifact, "", "\t")
+	if err != nil {
+		log.Fatal(err)
+	}
+	refsIndexArtifactDigest = godigest.FromBytes(refsIndexArtifactContent).String()
+
 	dummyDigest = godigest.FromString("hello world").String()
 
 	errorCodes = []string{