1 files changed, 2 insertions, 0 deletions
diff --git a/resources/src/mediawiki.language/mediawiki.language.init.js b/resources/src/mediawiki.language/mediawiki.language.init.js
index df95d751..b3765c85 100644
--- a/resources/src/mediawiki.language/mediawiki.language.init.js
+++ b/resources/src/mediawiki.language/mediawiki.language.init.js
@@ -54,6 +54,7 @@
 		 */
 		getData: function ( langCode, dataKey ) {
 			var langData = mw.language.data;
+			langCode = langCode.toLowerCase();
 			if ( langData && langData[langCode] instanceof mw.Map ) {
 				return langData[langCode].get( dataKey );
 			}
@@ -71,6 +72,7 @@
 		 */
 		setData: function ( langCode, dataKey, value ) {
 			var langData = mw.language.data;
+			langCode = langCode.toLowerCase();
 			if ( !( langData[langCode] instanceof mw.Map ) ) {
 				langData[langCode] = new mw.Map();
 			}