--- a/www-client/firefox/firefox-64.0.ebuild +++ a/www-client/firefox/firefox-64.0.ebuild @@ -462,7 +462,7 @@ src_configure() { } src_compile() { - MOZ_MAKE_FLAGS="${MAKEOPTS}" SHELL="${SHELL:-${EPREFIX}/bin/bash}" MOZ_NOSPAM=1 \ + MOZ_MAKE_FLAGS="${MAKEOPTS} -O" SHELL="${SHELL:-${EPREFIX}/bin/bash}" MOZ_NOSPAM=1 \ ./mach build --verbose || die }