diff --git a/crates/crates-io/lib.rs b/crates/crates-io/lib.rs
index b1dbd59c485..d95ce91c888 100644
--- a/crates/crates-io/lib.rs
+++ b/crates/crates-io/lib.rs
@@ -244,7 +244,7 @@ impl Registry {
 
     pub fn add_owners(&mut self, krate: &str, owners: &[&str]) -> Result<String> {
         let body = serde_json::to_string(&OwnersReq { users: owners })?;
-        let body = self.put(&format!("/crates/{}/owners", krate), body.as_bytes())?;
+        let body = self.put(&format!("/crates/{}/owners", krate), Some(body.as_bytes()))?;
         assert!(serde_json::from_str::<OwnerResponse>(&body)?.ok);
         Ok(serde_json::from_str::<OwnerResponse>(&body)?.msg)
     }
@@ -293,6 +293,7 @@ impl Registry {
         self.handle.url(&url)?;
         self.handle.in_filesize(size as u64)?;
         let mut headers = List::new();
+        headers.append("Content-Type: application/octet-stream")?;
         headers.append("Accept: application/json")?;
         headers.append(&format!("Authorization: {}", self.token()?))?;
         self.handle.http_headers(headers)?;
@@ -364,14 +365,14 @@ impl Registry {
     }
 
     pub fn unyank(&mut self, krate: &str, version: &str) -> Result<()> {
-        let body = self.put(&format!("/crates/{}/{}/unyank", krate, version), &[])?;
+        let body = self.put(&format!("/crates/{}/{}/unyank", krate, version), None)?;
         assert!(serde_json::from_str::<R>(&body)?.ok);
         Ok(())
     }
 
-    fn put(&mut self, path: &str, b: &[u8]) -> Result<String> {
+    fn put(&mut self, path: &str, b: Option<&[u8]>) -> Result<String> {
         self.handle.put(true)?;
-        self.req(path, Some(b), Auth::Authorized)
+        self.req(path, b, Auth::Authorized)
     }
 
     fn get(&mut self, path: &str) -> Result<String> {
diff --git a/src/doc/src/reference/registry-web-api.md b/src/doc/src/reference/registry-web-api.md
index e8481b3a4b1..b9100d55ca9 100644
--- a/src/doc/src/reference/registry-web-api.md
+++ b/src/doc/src/reference/registry-web-api.md
@@ -38,19 +38,21 @@ be null. The endpoints are versioned with the `v1` component of the path, and
 Cargo is responsible for handling backwards compatibility fallbacks should any
 be required in the future.
 
-Cargo sets the following headers for all requests:
+Cargo sets the `User-Agent` header for all requests to the Cargo version such
+as `cargo/1.32.0 (8610973aa 2019-01-02)`. This may be modified by the user in
+a configuration value. Added in 1.29.
 
-- `Content-Type`: `application/json` (for requests with a body payload)
-- `Accept`: `application/json`
-- `User-Agent`: The Cargo version such as `cargo/1.32.0 (8610973aa
-  2019-01-02)`. This may be modified by the user in a configuration value.
-  Added in 1.29.
+Other headers vary by endpoint and are documented below.
 
 ## Publish
 
 - Endpoint: `/api/v1/crates/new`
 - Method: PUT
 - Authorization: Included
+- Headers:
+    - `Content-Type`: `application/octet-stream`
+    - `Accept`: `application/json`
+- Body: Included (see below)
 
 The publish endpoint is used to publish a new version of a crate. The server
 should validate the crate, make it available for download, and add it to the
@@ -188,6 +190,9 @@ A successful response includes the JSON object:
 - Endpoint: `/api/v1/crates/{crate_name}/{version}/yank`
 - Method: DELETE
 - Authorization: Included
+- Headers:
+    - `Accept`: `application/json`
+- Body: None
 
 The yank endpoint will set the `yank` field of the given version of a crate to
 `true` in the index.
@@ -206,6 +211,9 @@ A successful response includes the JSON object:
 - Endpoint: `/api/v1/crates/{crate_name}/{version}/unyank`
 - Method: PUT
 - Authorization: Included
+- Headers:
+    - `Accept`: `application/json`
+- Body: None
 
 The unyank endpoint will set the `yank` field of the given version of a crate
 to `false` in the index.
@@ -232,6 +240,9 @@ how [crates.io] handles owners via GitHub users and teams.
 - Endpoint: `/api/v1/crates/{crate_name}/owners`
 - Method: GET
 - Authorization: Included
+- Headers:
+    - `Accept`: `application/json`
+- Body: None
 
 The owners endpoint returns a list of owners of the crate.
 
@@ -259,6 +270,10 @@ A successful response includes the JSON object:
 - Endpoint: `/api/v1/crates/{crate_name}/owners`
 - Method: PUT
 - Authorization: Included
+- Headers:
+    - `Content-Type`: `application/json`
+    - `Accept`: `application/json`
+- Body: Included (see below)
 
 A PUT request will send a request to the registry to add a new owner to a
 crate. It is up to the registry how to handle the request. For example,
@@ -290,6 +305,10 @@ A successful response includes the JSON object:
 - Endpoint: `/api/v1/crates/{crate_name}/owners`
 - Method: DELETE
 - Authorization: Included
+- Headers:
+    - `Content-Type`: `application/json`
+    - `Accept`: `application/json`
+- Body: Included (see below)
 
 A DELETE request will remove an owner from a crate. The request should include
 the following JSON object:
@@ -316,6 +335,10 @@ A successful response includes the JSON object:
 
 - Endpoint: `/api/v1/crates`
 - Method: GET
+- Authorization: Not Included
+- Headers:
+    - `Accept`: `application/json`
+- Body: None
 - Query Parameters:
     - `q`: The search query string.
     - `per_page`: Number of results, default 10, max 100.