diff --git a/src/wp-includes/formatting.php b/src/wp-includes/formatting.php
index eacc2600d0..a3dd9c7563 100644
--- a/src/wp-includes/formatting.php
+++ b/src/wp-includes/formatting.php
@@ -4141,7 +4141,7 @@ function print_emoji_detection_script() {
 
 	$version = 'ver=' . $wp_version;
 
-	if ( SCRIPT_DEBUG ) {
+	if ( defined( 'SCRIPT_DEBUG' ) && SCRIPT_DEBUG ) {
 		$settings['source'] = array(
 			/** This filter is documented in wp-includes/class.wp-scripts.php */
 			'wpemoji' => apply_filters( 'script_loader_src', includes_url( "js/wp-emoji.js?$version" ), 'wpemoji' ),