Index: src/org/w3c/unicorn/action/LanguageAction.java
===================================================================
--- src/org/w3c/unicorn/action/LanguageAction.java	(revision 1353:6bebf2fa4d92)
+++ src/org/w3c/unicorn/action/LanguageAction.java	(revision 1463:b6edc11943a5)
@@ -313,5 +313,5 @@
 			OutputFormater fileOutputFormater;
 			if (interfaceChanged) {
-				fileOutputFormater = new FileOutputFormater("language.properties", Property.get("DEFAULT_LANGUAGE"), "text/plain", languageParameter + ".properties");
+				fileOutputFormater = new FileOutputFormater("language.properties", Property.get("DEFAULT_LANGUAGE"), "text/plain", languageParameter.replace("_", "-") + ".properties");
 				outputFormaters.add(fileOutputFormater);
 			}
@@ -319,5 +319,5 @@
 			OutputFormater fileOutputFormater2;
 			if (tasklistChanged) {
-				fileOutputFormater2 = new FileOutputFormater("tasklist.properties", Property.get("DEFAULT_LANGUAGE"), "text/plain", languageParameter + ".tasklist.properties");
+				fileOutputFormater2 = new FileOutputFormater("tasklist.properties", Property.get("DEFAULT_LANGUAGE"), "text/plain", languageParameter.replace("_", "-") + ".tasklist.properties");
 				outputFormaters.add(fileOutputFormater2);
 			}