diff --git a/src/wp-includes/class-wp.php b/src/wp-includes/class-wp.php
index 8c7c48b3b2..770df083e7 100644
--- a/src/wp-includes/class-wp.php
+++ b/src/wp-includes/class-wp.php
@@ -170,8 +170,13 @@ class WP {
 
 			list( $req_uri ) = explode( '?', $_SERVER['REQUEST_URI'] );
 			$self            = $_SERVER['PHP_SELF'];
-			$home_path       = trim( parse_url( home_url(), PHP_URL_PATH ), '/' );
-			$home_path_regex = sprintf( '|^%s|i', preg_quote( $home_path, '|' ) );
+
+			$home_path       = parse_url( home_url(), PHP_URL_PATH );
+			$home_path_regex = '';
+			if ( is_string( $home_path ) && '' !== $home_path ) {
+				$home_path       = trim( $home_path, '/' );
+				$home_path_regex = sprintf( '|^%s|i', preg_quote( $home_path, '|' ) );
+			}
 
 			/*
 			 * Trim path info from the end and the leading home path from the front.
@@ -180,14 +185,17 @@ class WP {
 			 */
 			$req_uri  = str_replace( $pathinfo, '', $req_uri );
 			$req_uri  = trim( $req_uri, '/' );
-			$req_uri  = preg_replace( $home_path_regex, '', $req_uri );
-			$req_uri  = trim( $req_uri, '/' );
-			$pathinfo = trim( $pathinfo, '/' );
-			$pathinfo = preg_replace( $home_path_regex, '', $pathinfo );
 			$pathinfo = trim( $pathinfo, '/' );
 			$self     = trim( $self, '/' );
-			$self     = preg_replace( $home_path_regex, '', $self );
-			$self     = trim( $self, '/' );
+
+			if ( ! empty( $home_path_regex ) ) {
+				$req_uri  = preg_replace( $home_path_regex, '', $req_uri );
+				$req_uri  = trim( $req_uri, '/' );
+				$pathinfo = preg_replace( $home_path_regex, '', $pathinfo );
+				$pathinfo = trim( $pathinfo, '/' );
+				$self     = preg_replace( $home_path_regex, '', $self );
+				$self     = trim( $self, '/' );
+			}
 
 			// The requested permalink is in $pathinfo for path info requests and
 			// $req_uri for other requests.
diff --git a/tests/phpunit/tests/wp/parseRequest.php b/tests/phpunit/tests/wp/parseRequest.php
new file mode 100644
index 0000000000..2f022d7d2d
--- /dev/null
+++ b/tests/phpunit/tests/wp/parseRequest.php
@@ -0,0 +1,42 @@
+<?php
+
+/**
+ * @group wp
+ * @covers WP::parse_request
+ */
+class Tests_WP_ParseRequest extends WP_UnitTestCase {
+	/**
+	 * @var WP
+	 */
+	protected $wp;
+
+	public function set_up() {
+		parent::set_up();
+		$this->wp = new WP();
+	}
+
+	/**
+	 * Test that PHP 8.1 "passing null to non-nullable" deprecation notice
+	 * is not thrown when the home URL has no path/trailing slash (default setup).
+	 *
+	 * Note: This does not test the actual functioning of the parse_request() method.
+	 * It just and only tests for/against the deprecation notice.
+	 *
+	 * @ticket 53635
+	 */
+	public function test_no_deprecation_notice_when_home_url_has_no_path() {
+		// Make sure rewrite rules are not empty.
+		$this->set_permalink_structure( '/%year%/%monthnum%/%postname%/' );
+
+		// Make sure the test will function independently of whatever the test user set in wp-tests-config.php.
+		add_filter(
+			'home_url',
+			static function ( $url ) {
+				return 'http://example.org';
+			}
+		);
+
+		$this->wp->parse_request();
+		$this->assertSame( '', $this->wp->request );
+	}
+}