diff --git a/_build.sh b/_build.sh
index 40fe97d60..fecffa1d7 100755
--- a/_build.sh
+++ b/_build.sh
@@ -76,6 +76,7 @@ set -o xtrace -o errexit -o nounset; [ -n "${BASH:-}${ZSH_NAME:-}" ] && set -o p
 # TODO:
 #   - Change default TLS to BoringSSL (with OPENSSL_SMALL?) or LibreSSL?
 #   - linux: use musl.
+#   - linux: fix/mitigate missing GLIBC versioned symbols on systems older than the build machine
 #   - mac: Test -DSHARE_LIB_OBJECT=ON with curl 8.3.0.
 #   - Rename _BRANCH to CW_CONFIG internally.
 #   - Replace .zip with .tar.gz for all-packages artifact (in _ul.sh)?