diff --git a/dev-ruby/mocha/mocha-2.0.1.ebuild b/dev-ruby/mocha/mocha-2.0.1.ebuild
index 2fe21c9e149b8..8b9904e74ec0f 100644
--- a/dev-ruby/mocha/mocha-2.0.1.ebuild
+++ b/dev-ruby/mocha/mocha-2.0.1.ebuild
@@ -18,7 +18,7 @@ SRC_URI="https://github.com/freerange/mocha/archive/v${PV}.tar.gz -> ${P}.tar.gz
 
 LICENSE="MIT"
 SLOT="$(ver_cut 1)"
-KEYWORDS="~amd64 ~arm ~arm64 ~hppa ~loong ~ppc ~ppc64 ~riscv ~sparc ~x86"
+KEYWORDS="~amd64 ~arm ~arm64 ~hppa ~loong ~ppc ~ppc64 ~riscv ~s390 ~sparc ~x86"
 IUSE=""
 
 ruby_add_rdepend ">=dev-ruby/ruby2_keywords-0.0.5"