diff --git a/meta-google/recipes-google/ncsi/ncsid-config.bb b/meta-google/recipes-google/ncsi/ncsid-config.bb
index 17a88f1..e5d7776 100644
--- a/meta-google/recipes-google/ncsi/ncsid-config.bb
+++ b/meta-google/recipes-google/ncsi/ncsid-config.bb
@@ -14,6 +14,11 @@
 FILES_${PN} += "${systemd_unitdir}"
 
 do_install_append() {
+  if [ -z "${NCSID_IF_NAME}" ]; then
+    echo "Missing NCSID_IF_NAME" >&2
+    exit 1
+  fi
+
   install -d -m0755 ${D}${sysconfdir}/sysctl.d
   echo "net.ipv6.conf.${NCSID_IF_NAME}.accept_dad=0" \
     >>${D}${sysconfdir}/sysctl.d/25-nodad.conf