diff --git a/www-client/firefox/firefox-118.0.1.ebuild b/www-client/firefox/firefox-118.0.1.ebuild
index 3accfeceaad7..1915c3bbe2f5 100644
--- a/www-client/firefox/firefox-118.0.1.ebuild
+++ b/www-client/firefox/firefox-118.0.1.ebuild
@@ -917,6 +917,8 @@ src_configure() {
 	if use hardened ; then
 		mozconfig_add_options_ac "+hardened" --enable-hardening
 		append-ldflags "-Wl,-z,relro -Wl,-z,now"
+
+		sed -i -e '/-D_FORTIFY_SOURCE=/s:2:3:' "${S}"/build/moz.configure/toolchain.configure || die
 	fi
 
 	local myaudiobackends=""