diff --git a/wp-includes/rest-api/class-wp-rest-request.php b/wp-includes/rest-api/class-wp-rest-request.php
index 74a81c92e8..0a26d0fe3d 100644
--- a/wp-includes/rest-api/class-wp-rest-request.php
+++ b/wp-includes/rest-api/class-wp-rest-request.php
@@ -286,6 +286,7 @@ class WP_REST_Request implements ArrayAccess {
 	 * @param string $key Header name.
 	 */
 	public function remove_header( $key ) {
+		$key = $this->canonicalize_header_name( $key );
 		unset( $this->headers[ $key ] );
 	}
 
diff --git a/wp-includes/version.php b/wp-includes/version.php
index caec658073..1d42c20ca4 100644
--- a/wp-includes/version.php
+++ b/wp-includes/version.php
@@ -4,7 +4,7 @@
  *
  * @global string $wp_version
  */
-$wp_version = '4.8-alpha-40576';
+$wp_version = '4.8-alpha-40577';
 
 /**
  * Holds the WordPress DB revision, increments when changes are made to the WordPress DB schema.