diff --git a/src/main/scala/li/cil/oc/client/Manual.scala b/src/main/scala/li/cil/oc/client/Manual.scala
index 0b4874b248..f81b02f89b 100644
--- a/src/main/scala/li/cil/oc/client/Manual.scala
+++ b/src/main/scala/li/cil/oc/client/Manual.scala
@@ -24,7 +24,7 @@ import scala.collection.mutable
 object Manual extends ManualAPI {
   final val LanguageKey = "%LANGUAGE%"
 
-  final val FallbackLanguage = "en_US"
+  final val FallbackLanguage = "en_us"
 
   class History(val path: String, var offset: Int = 0)