--- a/firefox-bin-4.0.ebuild	2011-04-02 15:20:49.000000000 +0200
+++ a/firefox-bin-4.0.ebuild	2011-04-02 15:20:24.000000000 +0200
@@ -130,9 +130,7 @@ 
 	local LANG=${linguas%% *}
 	if [[ -n ${LANG} && ${LANG} != "en" ]]; then
 		elog "Setting default locale to ${LANG}"
-		sed -e "s:general.useragent.locale\", \"en-US\":general.useragent.locale\", \"${LANG}\":" \
-			-i "${D}${MOZILLA_FIVE_HOME}"/defaults/pref/${MY_PN}.js \
-			-i "${D}${MOZILLA_FIVE_HOME}"/defaults/pref/${MY_PN}-l10n.js || \
+                echo "pref(\"general.useragent.locale\", \"${LANG}\");" > "${D}${MOZILLA_FIVE_HOME}"/defaults/pref/${MY_PN}.js || \
 			die "sed failed to change locale"
 	fi