diff --git a/dev-python/nbformat/nbformat-5.1.3.ebuild b/dev-python/nbformat/nbformat-5.1.3.ebuild
index 79a3f09c3b66d..209b2d6cb3c32 100644
--- a/dev-python/nbformat/nbformat-5.1.3.ebuild
+++ b/dev-python/nbformat/nbformat-5.1.3.ebuild
@@ -18,7 +18,7 @@ SRC_URI="
 
 LICENSE="BSD"
 SLOT="0"
-KEYWORDS="amd64 ~arm arm64 ~ppc ppc64 ~riscv ~sparc x86"
+KEYWORDS="amd64 ~arm arm64 ~ppc ppc64 ~riscv ~s390 ~sparc x86"
 
 RDEPEND="
 	>=dev-python/jsonschema-2.4.0[${PYTHON_USEDEP}]