diff --git a/.gitignore b/.gitignore
index 7b3dea9..876025b 100644
--- a/.gitignore
+++ b/.gitignore
@@ -14,4 +14,7 @@ _book
 *.epub
 *.mobi
 *.pdf
-.idea
\ No newline at end of file
+.idea
+.vscode
+vendor
+composer.lock
\ No newline at end of file
diff --git a/inc/class-client.php b/inc/class-client.php
index ddba759..31e588c 100644
--- a/inc/class-client.php
+++ b/inc/class-client.php
@@ -229,8 +229,8 @@ public function check_redirect_uri( $uri ) {
 	 *
 	 * @return Authorization_Code|WP_Error
 	 */
-	public function generate_authorization_code( WP_User $user ) {
-		return Authorization_Code::create( $this, $user );
+	public function generate_authorization_code( WP_User $user, $data ) {
+		return Authorization_Code::create( $this, $user, $data );
 	}
 
 	/**
diff --git a/inc/endpoints/class-token.php b/inc/endpoints/class-token.php
index 6b24a82..54e28db 100644
--- a/inc/endpoints/class-token.php
+++ b/inc/endpoints/class-token.php
@@ -71,7 +71,7 @@ public function exchange_token( WP_REST_Request $request ) {
 			return $auth_code;
 		}
 
-		$is_valid = $auth_code->validate();
+		$is_valid = $auth_code->validate( $request );
 		if ( is_wp_error( $is_valid ) ) {
 			// Invalid request, but code itself exists, so we should delete
 			// (and silently ignore errors).
diff --git a/inc/tokens/class-authorization-code.php b/inc/tokens/class-authorization-code.php
index e5f212e..d4e027f 100644
--- a/inc/tokens/class-authorization-code.php
+++ b/inc/tokens/class-authorization-code.php
@@ -108,6 +108,43 @@ public function get_expiration() {
 		return (int) $value['expiration'];
 	}
 
+	/**
+	 * Validate whether the redirect_uri matches the one in the initial OAuth2 request
+	 *
+	 * @param String $redirect_uri
+	 * @return Boolean|WP_Error
+	 */
+	protected function validate_redirect_uri( $redirect_uri ) {
+		$value = $this->get_value();
+
+		if ( ! empty( $value['redirect_uri'] ) && ! empty( $redirect_uri ) ) {
+			if ( $value['redirect_uri'] !== $redirect_uri ) {
+				return new WP_Error(
+					'oauth2.tokens.authorization_code.redirect_uri.mismatch',
+					__( 'redirect_uri does not match the one in the initial request.', 'oauth2' ),
+					[
+						'status' => WP_Http::BAD_REQUEST,
+					]
+				);
+			}
+		}
+
+		if ( ( empty( $value['redirect_uri'] ) && ! empty( $redirect_uri ) && ! $this->client->check_redirect_uri( $redirect_uri ) ) ||
+			( ! empty( $value['redirect_uri'] ) && empty( $redirect_uri ) ) ) {
+			return new WP_Error(
+				'oauth2.tokens.authorization_code.redirect_uri.mismatch',
+				__( 'redirect_uri does not match the one in the initial request.', 'oauth2' ),
+				[
+					'status' => WP_Http::BAD_REQUEST,
+					'expiration' => $expiration,
+					'time' => $now,
+				]
+			);
+		}
+
+		return true;
+	}
+
 	/**
 	 * Validate the code for use.
 	 *
@@ -129,6 +166,11 @@ public function validate( $args = [] ) {
 			);
 		}
 
+		$redirect_uri = $this->validate_redirect_uri( $args['redirect_uri'] );
+		if ( is_wp_error( $redirect_uri ) ) {
+			return $redirect_uri;
+		}
+
 		return true;
 	}
 
@@ -183,12 +225,13 @@ public static function get_by_code( Client $client, $code ) {
 	 *
 	 * @return Authorization_Code|WP_Error Authorization code instance, or error on failure.
 	 */
-	public static function create( Client $client, WP_User $user ) {
+	public static function create( Client $client, WP_User $user, $redirect_uri = '' ) {
 		$code = wp_generate_password( static::KEY_LENGTH, false );
 		$meta_key = static::KEY_PREFIX . $code;
 		$data = [
-			'user'       => (int) $user->ID,
-			'expiration' => time() + static::MAX_AGE,
+			'user'       	=> (int) $user->ID,
+			'expiration' 	=> time() + static::MAX_AGE,
+			'redirect_uri' 	=> $redirect_uri,
 		];
 		$result = add_post_meta( $client->get_post_id(), wp_slash( $meta_key ), wp_slash( $data ), true );
 		if ( ! $result ) {
diff --git a/inc/types/class-authorization-code.php b/inc/types/class-authorization-code.php
index cff7e86..446556c 100644
--- a/inc/types/class-authorization-code.php
+++ b/inc/types/class-authorization-code.php
@@ -33,7 +33,8 @@ protected function handle_authorization_submission( $submit, Client $client, $da
 			case 'authorize':
 				// Generate authorization code and redirect back.
 				$user = wp_get_current_user();
-				$code = $client->generate_authorization_code( $user );
+				$code = $client->generate_authorization_code( $user, $redirect_uri );
+
 				if ( is_wp_error( $code ) ) {
 					return $code;
 				}
diff --git a/inc/types/class-base.php b/inc/types/class-base.php
index cde81a1..2dc8bcb 100644
--- a/inc/types/class-base.php
+++ b/inc/types/class-base.php
@@ -52,9 +52,12 @@ public function handle_authorisation() {
 		}
 
 		// Validate the redirection URI.
-		$redirect_uri = $this->validate_redirect_uri( $client, $redirect_uri );
-		if ( is_wp_error( $redirect_uri ) ) {
-			return $redirect_uri;
+		if ( ! empty( $redirect_uri ) ) {
+			$redirect_uri = $this->validate_redirect_uri( $client, $redirect_uri );
+
+			if ( is_wp_error( $redirect_uri ) ) {
+				return $redirect_uri;
+			}
 		}
 
 		// Valid parameters, ensure the user is logged in.
@@ -69,8 +72,7 @@ public function handle_authorisation() {
 		}
 
 		// Check nonce.
-		$nonce_action = $this->get_nonce_action( $client );
-		if ( ! wp_verify_nonce( wp_unslash( $_POST['_wpnonce'] ), $none_action ) ) {
+		if ( ! wp_verify_nonce( wp_unslash( $_POST['_wpnonce'] ), $this->get_nonce_action( $client ) ) ) {
 			return new WP_Error(
 				'oauth2.types.authorization_code.handle_authorisation.invalid_nonce',
 				__( 'Invalid nonce.', 'oauth2' )
@@ -105,24 +107,11 @@ public function handle_authorisation() {
 	 * @return string|WP_Error Valid redirect URI on success, error otherwise.
 	 */
 	protected function validate_redirect_uri( Client $client, $redirect_uri = null ) {
-		if ( empty( $redirect_uri ) ) {
-			$registered = $client->get_redirect_uris();
-			if ( count( $registered ) !== 1 ) {
-				// Either none registered, or more than one, so error.
-				return new WP_Error(
-					'oauth2.types.authorization_code.handle_authorisation.missing_redirect_uri',
-					__( 'Redirect URI was required, but not found.', 'oauth2' )
-				);
-			}
-
-			$redirect_uri = $registered[0];
-		} else {
-			if ( ! $client->check_redirect_uri( $redirect_uri ) ) {
-				return new WP_Error(
-					'oauth2.types.authorization_code.handle_authorisation.invalid_redirect_uri',
-					__( 'Specified redirect URI is not valid for this client.', 'oauth2' )
-				);
-			}
+		if ( ! $client->check_redirect_uri( $redirect_uri ) ) {
+			return new WP_Error(
+				'oauth2.types.authorization_code.handle_authorisation.invalid_redirect_uri',
+				__( 'Specified redirect URI is not valid for this client.', 'oauth2' )
+			);
 		}
 
 		return $redirect_uri;