diff --git a/src/wp-includes/customize/class-wp-customize-selective-refresh.php b/src/wp-includes/customize/class-wp-customize-selective-refresh.php
index 23d5a94885..6c04a73698 100644
--- a/src/wp-includes/customize/class-wp-customize-selective-refresh.php
+++ b/src/wp-includes/customize/class-wp-customize-selective-refresh.php
@@ -324,10 +324,13 @@ final class WP_Customize_Selective_Refresh {
 		 */
 		if ( ! is_customize_preview() ) {
 			wp_send_json_error( 'expected_customize_preview', 403 );
-		} else if ( ! isset( $_POST['partials'] ) ) {
+		} elseif ( ! isset( $_POST['partials'] ) ) {
 			wp_send_json_error( 'missing_partials', 400 );
 		}
 
+		// Ensure that doing selective refresh on 404 template doesn't result in fallback rendering behavior (full refreshes).
+		status_header( 200 );
+
 		$partials = json_decode( wp_unslash( $_POST['partials'] ), true );
 
 		if ( ! is_array( $partials ) ) {