diff --git a/platform/javascript/js/engine/config.js b/platform/javascript/js/engine/config.js
index 2e5e1ed0d1a2..9c4b6c201297 100644
--- a/platform/javascript/js/engine/config.js
+++ b/platform/javascript/js/engine/config.js
@@ -334,6 +334,7 @@ const InternalConfig = function (initConfig) { // eslint-disable-line no-unused-
 			locale = navigator.languages ? navigator.languages[0] : navigator.language;
 			locale = locale.split('.')[0];
 		}
+		locale = locale.replace('-', '_');
 		const onExit = this.onExit;
 
 		// Godot configuration.