diff --git a/sdk_container/src/third_party/coreos-overlay/profiles/coreos/base/package.accept_keywords b/sdk_container/src/third_party/coreos-overlay/profiles/coreos/base/package.accept_keywords
index fe9bd4c29a..508238d3ef 100644
--- a/sdk_container/src/third_party/coreos-overlay/profiles/coreos/base/package.accept_keywords
+++ b/sdk_container/src/third_party/coreos-overlay/profiles/coreos/base/package.accept_keywords
@@ -75,6 +75,9 @@
 # get stabilized in Gentoo.
 =dev-libs/yajl-2.1.0-r5 ~amd64 ~arm64
 
+# Keep versions on both arches in sync.
+=dev-python/cython-3.0.11 ~arm64
+
 # Catalyst 4 is not stable yet, but earlier versions are masked now.
 dev-util/catalyst ~amd64 ~arm64