diff --git a/pkg/api/controller_test.go b/pkg/api/controller_test.go
index 4540002c..b9af61ba 100644
--- a/pkg/api/controller_test.go
+++ b/pkg/api/controller_test.go
@@ -4145,12 +4145,12 @@ func TestImageSignatures(t *testing.T) {
 			resp, err = resty.R().Get(
 				fmt.Sprintf("%s/oras/artifacts/v1/%s/manifests/%s/referrers", baseURL, repoName, digest.String()))
 			So(err, ShouldBeNil)
-			So(resp.StatusCode(), ShouldEqual, http.StatusBadRequest)
+			So(resp.StatusCode(), ShouldEqual, http.StatusNotFound)
 
 			resp, err = resty.R().SetQueryParam("artifactType", "badArtifact").Get(
 				fmt.Sprintf("%s/oras/artifacts/v1/%s/manifests/%s/referrers", baseURL, repoName, digest.String()))
 			So(err, ShouldBeNil)
-			So(resp.StatusCode(), ShouldEqual, http.StatusBadRequest)
+			So(resp.StatusCode(), ShouldEqual, http.StatusNotFound)
 
 			resp, err = resty.R().SetQueryParam("artifactType", notreg.ArtifactTypeNotation).Get(
 				fmt.Sprintf("%s/oras/artifacts/v1/%s/manifests/%s/referrers", baseURL, "badRepo", digest.String()))
diff --git a/pkg/api/routes.go b/pkg/api/routes.go
index f8f492ad..72f00a52 100644
--- a/pkg/api/routes.go
+++ b/pkg/api/routes.go
@@ -23,7 +23,6 @@ import (
 
 	"github.com/gorilla/mux"
 	jsoniter "github.com/json-iterator/go"
-	notreg "github.com/notaryproject/notation-go/registry"
 	"github.com/opencontainers/distribution-spec/specs-go/v1/extensions"
 	godigest "github.com/opencontainers/go-digest"
 	ispec "github.com/opencontainers/image-spec/specs-go/v1"
@@ -1687,13 +1686,6 @@ func (rh *RouteHandler) GetOrasReferrers(response http.ResponseWriter, request *
 		artifactType = artifactTypes[0]
 	}
 
-	if artifactType != notreg.ArtifactTypeNotation {
-		rh.c.Log.Error().Str("artifactType", artifactType).Msg("invalid artifact type")
-		response.WriteHeader(http.StatusBadRequest)
-
-		return
-	}
-
 	imgStore := rh.getImageStore(name)
 
 	rh.c.Log.Info().Str("digest", digest.String()).Str("artifactType", artifactType).Msg("getting manifest")