diff --git a/src/wp-includes/canonical.php b/src/wp-includes/canonical.php
index 6a74ac2d43..167b5cf562 100644
--- a/src/wp-includes/canonical.php
+++ b/src/wp-includes/canonical.php
@@ -895,7 +895,12 @@ function redirect_guess_404_permalink() {
 
 		// If any of post_type, year, monthnum, or day are set, use them to refine the query.
 		if ( get_query_var( 'post_type' ) ) {
-			$where .= $wpdb->prepare( ' AND post_type = %s', get_query_var( 'post_type' ) );
+			if ( is_array( get_query_var( 'post_type' ) ) ) {
+				// phpcs:ignore WordPress.DB.PreparedSQLPlaceholders.UnfinishedPrepare
+				$where .= " AND post_type IN ('" . join( "', '", esc_sql( get_query_var( 'post_type' ) ) ) . "')";
+			} else {
+				$where .= $wpdb->prepare( ' AND post_type = %s', get_query_var( 'post_type' ) );
+			}
 		} else {
 			$where .= " AND post_type IN ('" . implode( "', '", get_post_types( array( 'public' => true ) ) ) . "')";
 		}
diff --git a/tests/phpunit/tests/canonical.php b/tests/phpunit/tests/canonical.php
index 895e5bb44e..bd0b68c038 100644
--- a/tests/phpunit/tests/canonical.php
+++ b/tests/phpunit/tests/canonical.php
@@ -275,6 +275,26 @@ class Tests_Canonical extends WP_Canonical_UnitTestCase {
 		$this->assertFalse( redirect_guess_404_permalink() );
 	}
 
+	/**
+	 * Ensure multiple post types do not throw a notice.
+	 *
+	 * @ticket 43056
+	 */
+	public function test_redirect_guess_404_permalink_post_types() {
+		/*
+		 * Sample-page is intentionally missspelt as sample-pag to ensure
+		 * the 404 post permalink guessing runs.
+		 *
+		 * Please do not correct the apparent typo.
+		 */
+
+		// String format post type.
+		$this->assertCanonical( '/?name=sample-pag&post_type=page', '/sample-page/' );
+		// Array formatted post type or types.
+		$this->assertCanonical( '/?name=sample-pag&post_type[]=page', '/sample-page/' );
+		$this->assertCanonical( '/?name=sample-pag&post_type[]=page&post_type[]=post', '/sample-page/' );
+	}
+
 	/**
 	 * @ticket 43745
 	 */