diff --git a/includes/openid-connect-generic-client-wrapper.php b/includes/openid-connect-generic-client-wrapper.php
index 28181cf..9c34cb3 100644
--- a/includes/openid-connect-generic-client-wrapper.php
+++ b/includes/openid-connect-generic-client-wrapper.php
@@ -121,7 +121,7 @@ class OpenID_Connect_Generic_Client_Wrapper {
 			return;
 		}
 
-		$current_time = current_time( 'timestamp', TRUE );
+		$current_time = current_time( 'timestamp', true );
 		$refresh_token_info = $session[ $this->cookie_token_refresh_key ];
 
 		$next_access_token_refresh_time = $refresh_token_info[ 'next_access_token_refresh_time' ];
@@ -261,7 +261,7 @@ class OpenID_Connect_Generic_Client_Wrapper {
 		}
 
 		if ( $this->settings->no_sslverify ) {
-			$request['sslverify'] = FALSE;
+			$request['sslverify'] = false;
 		}
 
 		return $request;
@@ -383,7 +383,7 @@ class OpenID_Connect_Generic_Client_Wrapper {
 		$this->logger->log( "Successful login for: {$user->user_login} ({$user->ID})", 'login-success' );
 
 		// redirect back to the origin page if enabled
-		$redirect_url = isset( $_COOKIE[ $this->cookie_redirect_key ] ) ? esc_url( $_COOKIE[ $this->cookie_redirect_key ] ) : FALSE;
+		$redirect_url = isset( $_COOKIE[ $this->cookie_redirect_key ] ) ? esc_url( $_COOKIE[ $this->cookie_redirect_key ] ) : false;
 
 		if( $this->settings->redirect_user_back && !empty( $redirect_url ) ) {
 			do_action( 'openid-connect-generic-redirect-user-back', $redirect_url, $user );
@@ -427,7 +427,7 @@ class OpenID_Connect_Generic_Client_Wrapper {
 		update_user_meta( $user->ID, 'openid-connect-generic-last-user-claim', $user_claim );
 
 		// Create the WP session, so we know its token
-		$expiration = time() + apply_filters( 'auth_cookie_expiration', 2 * DAY_IN_SECONDS, $user->ID, FALSE );
+		$expiration = time() + apply_filters( 'auth_cookie_expiration', 2 * DAY_IN_SECONDS, $user->ID, false );
 		$manager = WP_Session_Tokens::get_instance( $user->ID );
 		$token = $manager->create( $expiration );
 
@@ -435,7 +435,7 @@ class OpenID_Connect_Generic_Client_Wrapper {
 		$this->save_refresh_token( $manager, $token, $token_response );
 
 		// you did great, have a cookie!
-		wp_set_auth_cookie( $user->ID, FALSE, '', $token);
+		wp_set_auth_cookie( $user->ID, false, '', $token);
 		do_action( 'wp_login', $user->user_login, $user );
 	}
 
@@ -448,7 +448,7 @@ class OpenID_Connect_Generic_Client_Wrapper {
 	 */
 	function save_refresh_token( $manager, $token, $token_response ) {
 		$session = $manager->get($token);
-		$now = current_time( 'timestamp' , TRUE );
+		$now = current_time( 'timestamp' , true );
 		$session[$this->cookie_token_refresh_key] = array(
 			'next_access_token_refresh_time' => $token_response['expires_in'] + $now,
 			'refresh_token' => isset( $token_response[ 'refresh_token' ] ) ? $token_response[ 'refresh_token' ] : false,
@@ -667,7 +667,7 @@ class OpenID_Connect_Generic_Client_Wrapper {
 				return new WP_Error( 'bad-user-claim-result', __( 'Bad user claim result' ), $user_claim_result );
 			}
 
-			$user_claim = json_decode( $user_claim_result['body'], TRUE );
+			$user_claim = json_decode( $user_claim_result['body'], true );
 		}
 
 		$_email = $this->get_email_from_claim( $user_claim, true );
@@ -712,7 +712,7 @@ class OpenID_Connect_Generic_Client_Wrapper {
 
 		// allow other plugins / themes to determine authorization 
 		// of new accounts based on the returned user claim
-		$create_user = apply_filters( 'openid-connect-generic-user-creation-test', TRUE, $user_claim );
+		$create_user = apply_filters( 'openid-connect-generic-user-creation-test', true, $user_claim );
 
 		if ( ! $create_user ) {
 			return new WP_Error( 'cannot-authorize', __( 'Can not authorize.' ), $create_user );
@@ -721,7 +721,7 @@ class OpenID_Connect_Generic_Client_Wrapper {
 		$user_claim = apply_filters( 'openid-connect-generic-alter-user-claim', $user_claim );
 		$user_data = array(
 			'user_login' => $username,
-			'user_pass' => wp_generate_password( 32, TRUE, TRUE ),
+			'user_pass' => wp_generate_password( 32, true, true ),
 			'user_email' => $email,
 			'display_name' => $displayname,
 			'nickname' => $nickname,
@@ -742,7 +742,7 @@ class OpenID_Connect_Generic_Client_Wrapper {
 		$user = get_user_by( 'id', $uid );
 
 		// save some meta data about this new user for the future
-		add_user_meta( $user->ID, 'openid-connect-generic-subject-identity', (string) $subject_identity, TRUE );
+		add_user_meta( $user->ID, 'openid-connect-generic-subject-identity', (string) $subject_identity, true );
 
 		// log the results
 		$this->logger->log( "New user created: {$user->user_login} ($uid)", 'success' );
@@ -764,7 +764,7 @@ class OpenID_Connect_Generic_Client_Wrapper {
 	 */
 	function update_existing_user( $uid, $subject_identity ) {
 		// add the OpenID Connect meta data 
-		add_user_meta( $uid, 'openid-connect-generic-subject-identity', (string) $subject_identity, TRUE );
+		add_user_meta( $uid, 'openid-connect-generic-subject-identity', (string) $subject_identity, true );
 		
 		// allow plugins / themes to take action on user update
 		do_action( 'openid-connect-generic-user-update', $uid );
diff --git a/includes/openid-connect-generic-client.php b/includes/openid-connect-generic-client.php
index 7b8b11c..35790c9 100644
--- a/includes/openid-connect-generic-client.php
+++ b/includes/openid-connect-generic-client.php
@@ -172,7 +172,7 @@ class OpenID_Connect_Generic_Client {
 		}
 
 		// extract token response from token
-		$token_response = json_decode( $token_result['body'], TRUE );
+		$token_response = json_decode( $token_result['body'], true );
 
 		if ( isset( $token_response[ 'error' ] ) ) {
 			$error = $token_response[ 'error' ];
@@ -254,7 +254,7 @@ class OpenID_Connect_Generic_Client {
 	 */
 	function check_state( $state ) {
 		$states = get_option( 'openid-connect-generic-valid-states', array() );
-		$valid  = FALSE;
+		$valid  = false;
 
 		// remove any expired states
 		foreach ( $states as $code => $timestamp ) {
@@ -267,7 +267,7 @@ class OpenID_Connect_Generic_Client {
 		if ( isset( $states[ $state ] ) ) {
 			// state is valid, remove it
 			unset( $states[ $state ] );
-			$valid = TRUE;
+			$valid = true;
 		}
 
 		// save our altered states
@@ -324,7 +324,7 @@ class OpenID_Connect_Generic_Client {
 					$tmp[1]
 				)
 			)
-			, TRUE
+			, true
 		);
 		
 		return $id_token_claim;
@@ -366,7 +366,7 @@ class OpenID_Connect_Generic_Client {
 			return new WP_Error( 'bad-claim', __( 'Bad user claim' ), $user_claim_result );
 		}
 
-		$user_claim = json_decode( $user_claim_result['body'], TRUE );
+		$user_claim = json_decode( $user_claim_result['body'], true );
 
 		return $user_claim;
 	}
@@ -401,7 +401,7 @@ class OpenID_Connect_Generic_Client {
 		}
 
 		// allow for other plugins to alter the login success
-		$login_user = apply_filters( 'openid-connect-generic-user-login-test', TRUE, $user_claim );
+		$login_user = apply_filters( 'openid-connect-generic-user-login-test', true, $user_claim );
 		
 		if ( ! $login_user ) {
 			return new WP_Error( 'unauthorized', __( 'Unauthorized access' ), $login_user );
diff --git a/includes/openid-connect-generic-login-form.php b/includes/openid-connect-generic-login-form.php
index 27bb7aa..011fa52 100644
--- a/includes/openid-connect-generic-login-form.php
+++ b/includes/openid-connect-generic-login-form.php
@@ -68,7 +68,7 @@ class OpenID_Connect_Generic_Login_Form {
 			$redirect_expiry = current_time('timestamp') + DAY_IN_SECONDS;
 
 			// default redirect to the homepage
-			$redirect_url = home_url( esc_url( add_query_arg( NULL, NULL ) ) );
+			$redirect_url = home_url( esc_url( add_query_arg( null, null ) ) );
 
 			if ( $GLOBALS['pagenow'] == 'wp-login.php' ) {
 				// if using the login form, default redirect to the admin dashboard
diff --git a/includes/openid-connect-generic-option-logger.php b/includes/openid-connect-generic-option-logger.php
index 1f72b18..165863a 100644
--- a/includes/openid-connect-generic-option-logger.php
+++ b/includes/openid-connect-generic-option-logger.php
@@ -175,7 +175,7 @@ class OpenID_Connect_Generic_Option_Logger {
 	private function save_logs( $logs ){
 		// save our logs
 		$this->logs = $logs;
-		return update_option( $this->option_name, $logs, FALSE );
+		return update_option( $this->option_name, $logs, false );
 	}
 
 	/**
diff --git a/includes/openid-connect-generic-settings-page.php b/includes/openid-connect-generic-settings-page.php
index 7ceeec1..53bb07c 100644
--- a/includes/openid-connect-generic-settings-page.php
+++ b/includes/openid-connect-generic-settings-page.php
@@ -273,7 +273,7 @@ class OpenID_Connect_Generic_Settings_Page {
 		foreach ( $this->settings_fields as $key => $field ) {
 			// make sure each key exists in the settings array
 			if ( ! isset( $this->settings->{ $key } ) ) {
-				$this->settings->{ $key } = NULL;
+				$this->settings->{ $key } = null;
 			}
 
 			// determine appropriate output callback