diff --git a/src/wp-includes/rest-api/endpoints/class-wp-rest-posts-controller.php b/src/wp-includes/rest-api/endpoints/class-wp-rest-posts-controller.php
index 26b78c5e35..89b4ccb3e2 100644
--- a/src/wp-includes/rest-api/endpoints/class-wp-rest-posts-controller.php
+++ b/src/wp-includes/rest-api/endpoints/class-wp-rest-posts-controller.php
@@ -1401,7 +1401,7 @@ class WP_REST_Posts_Controller extends WP_REST_Controller {
 			// #38883).  In this case, shim the value based on the `post_date`
 			// field with the site's timezone offset applied.
 			if ( '0000-00-00 00:00:00' === $post->post_date_gmt ) {
-				$post_date_gmt = date( 'Y-m-d H:i:s', strtotime( $post->post_date ) - ( get_option( 'gmt_offset' ) * 3600 ) );
+				$post_date_gmt = get_gmt_from_date( $post->post_date );
 			} else {
 				$post_date_gmt = $post->post_date_gmt;
 			}
diff --git a/tests/phpunit/tests/rest-api/rest-posts-controller.php b/tests/phpunit/tests/rest-api/rest-posts-controller.php
index abc30d40ce..409982eed8 100644
--- a/tests/phpunit/tests/rest-api/rest-posts-controller.php
+++ b/tests/phpunit/tests/rest-api/rest-posts-controller.php
@@ -2242,8 +2242,7 @@ class WP_Test_REST_Posts_Controller extends WP_Test_REST_Post_Type_Controller_Te
 		global $wpdb;
 
 		wp_set_current_user( self::$editor_id );
-		update_option( 'timezone_string', '' );
-		update_option( 'gmt_offset', -6 );
+		update_option( 'timezone_string', 'America/Chicago' );
 
 		// Need to set dates using wpdb directly because `wp_update_post` and
 		// `wp_insert_post` have additional validation on dates.
@@ -2288,7 +2287,6 @@ class WP_Test_REST_Posts_Controller extends WP_Test_REST_Post_Type_Controller_Te
 		$this->assertEquals( $post->post_date_gmt, '2016-02-23 19:00:00' );
 
 		update_option( 'timezone_string', '' );
-		update_option( 'gmt_offset', 0 );
 	}
 
 	public function test_update_post_slug() {