diff --git a/specs-go/v1/descriptor.go b/specs-go/v1/descriptor.go
index fdf50c744..c461647ef 100644
--- a/specs-go/v1/descriptor.go
+++ b/specs-go/v1/descriptor.go
@@ -17,7 +17,8 @@ package v1
 import digest "github.com/opencontainers/go-digest"
 
 // Descriptor describes the disposition of targeted content.
-// This structure provides `application/vnd.oci.descriptor.v1+json` mediatype when marshalled to JSON
+// This structure provides `application/vnd.oci.descriptor.v1+json` mediatype
+// when marshalled to JSON.
 type Descriptor struct {
 	// MediaType is the media type of the object this schema refers to.
 	MediaType string `json:"mediaType,omitempty"`
@@ -33,4 +34,35 @@ type Descriptor struct {
 
 	// Annotations contains arbitrary metadata relating to the targeted content.
 	Annotations map[string]string `json:"annotations,omitempty"`
+
+	// Platform describes the platform which the image in the manifest runs on.
+	//
+	// This should only be used when referring to a manifest.
+	Platform *Platform `json:"platform,omitempty"`
+}
+
+// Platform describes the platform which the image in the manifest runs on.
+type Platform struct {
+	// Architecture field specifies the CPU architecture, for example
+	// `amd64` or `ppc64`.
+	Architecture string `json:"architecture"`
+
+	// OS specifies the operating system, for example `linux` or `windows`.
+	OS string `json:"os"`
+
+	// OSVersion is an optional field specifying the operating system
+	// version, for example `10.0.10586`.
+	OSVersion string `json:"os.version,omitempty"`
+
+	// OSFeatures is an optional field specifying an array of strings,
+	// each listing a required OS feature (for example on Windows `win32k`).
+	OSFeatures []string `json:"os.features,omitempty"`
+
+	// Variant is an optional field specifying a variant of the CPU, for
+	// example `ppc64le` to specify a little-endian version of a PowerPC CPU.
+	Variant string `json:"variant,omitempty"`
+
+	// Features is an optional field specifying an array of strings, each
+	// listing a required CPU feature (for example `sse4` or `aes`).
+	Features []string `json:"features,omitempty"`
 }
diff --git a/specs-go/v1/index.go b/specs-go/v1/index.go
index 8fa889aa0..4e6c4b236 100644
--- a/specs-go/v1/index.go
+++ b/specs-go/v1/index.go
@@ -16,47 +16,13 @@ package v1
 
 import "github.com/opencontainers/image-spec/specs-go"
 
-// Platform describes the platform which the image in the manifest runs on.
-type Platform struct {
-	// Architecture field specifies the CPU architecture, for example
-	// `amd64` or `ppc64`.
-	Architecture string `json:"architecture"`
-
-	// OS specifies the operating system, for example `linux` or `windows`.
-	OS string `json:"os"`
-
-	// OSVersion is an optional field specifying the operating system
-	// version, for example `10.0.10586`.
-	OSVersion string `json:"os.version,omitempty"`
-
-	// OSFeatures is an optional field specifying an array of strings,
-	// each listing a required OS feature (for example on Windows `win32k`).
-	OSFeatures []string `json:"os.features,omitempty"`
-
-	// Variant is an optional field specifying a variant of the CPU, for
-	// example `ppc64le` to specify a little-endian version of a PowerPC CPU.
-	Variant string `json:"variant,omitempty"`
-
-	// Features is an optional field specifying an array of strings, each
-	// listing a required CPU feature (for example `sse4` or `aes`).
-	Features []string `json:"features,omitempty"`
-}
-
-// ManifestDescriptor describes a platform specific manifest.
-type ManifestDescriptor struct {
-	Descriptor
-
-	// Platform describes the platform which the image in the manifest runs on.
-	Platform *Platform `json:"platform,omitempty"`
-}
-
 // Index references manifests for various platforms.
 // This structure provides `application/vnd.oci.image.index.v1+json` mediatype when marshalled to JSON.
 type Index struct {
 	specs.Versioned
 
 	// Manifests references platform specific manifests.
-	Manifests []ManifestDescriptor `json:"manifests"`
+	Manifests []Descriptor `json:"manifests"`
 
 	// Annotations contains arbitrary metadata for the image index.
 	Annotations map[string]string `json:"annotations,omitempty"`