diff --git a/spec.md b/spec.md
index 5f6f1cfa..27af90a3 100644
--- a/spec.md
+++ b/spec.md
@@ -161,9 +161,11 @@ Throughout this document, `<reference>` as a tag MUST be at most 128 characters
 
 The client SHOULD include an `Accept` header indicating which manifest content types it supports.
 In a successful response, the `Content-Type` header will indicate the type of the returned manifest.
+The registry SHOULD NOT include parameters on the `Content-Type` header.
+The client SHOULD ignore parameters on the `Content-Type` header.
 The `Content-Type` header SHOULD match what the client [pushed as the manifest's `Content-Type`](#pushing-manifests).
 If the manifest has a `mediaType` field, clients SHOULD reject unless the `mediaType` field's value matches the type specified by the `Content-Type` header.
-For more information on the use of `Accept` headers and content negotiation, please see [Content Negotiation](./content-negotiation.md).
+For more information on the use of `Accept` headers and content negotiation, please see [Content Negotiation](./content-negotiation.md) and [RFC7231](https://www.rfc-editor.org/rfc/rfc7231#section-3.1.1.1).
 
 A GET request to an existing manifest URL MUST provide the expected manifest, with a response code that MUST be `200 OK`.
 A successful response SHOULD contain the digest of the uploaded blob in the header `Docker-Content-Digest`.
@@ -442,6 +444,8 @@ This indicates that the upload session has begun and that the client MAY proceed
 To push a manifest, perform a `PUT` request to a path in the following format, and with the following headers and body: `/v2/<name>/manifests/<reference>` <sup>[end-7](#endpoints)</sup>
 
 Clients SHOULD set the `Content-Type` header to the type of the manifest being pushed.
+The client SHOULD NOT include parameters on the `Content-Type` header (see [RFC7231](https://www.rfc-editor.org/rfc/rfc7231#section-3.1.1.1)).
+The registry SHOULD ignore parameters on the `Content-Type` header.
 All manifests SHOULD include a `mediaType` field declaring the type of the manifest being pushed.
 If a manifest includes a `mediaType` field, clients MUST set the `Content-Type` header to the value specified by the `mediaType` field.