diff --git a/cluster/gce/util.sh b/cluster/gce/util.sh
index ddba646ddaf..17cabc423a4 100755
--- a/cluster/gce/util.sh
+++ b/cluster/gce/util.sh
@@ -429,7 +429,7 @@ function build-kube-env {
 
   rm -f ${file}
   cat >$file <<EOF
-ENV_TIMESTAMP: $(yaml-quote $(date -uIs))
+ENV_TIMESTAMP: $(yaml-quote $(date -u +%Y-%m-%dT%T%z))
 INSTANCE_PREFIX: $(yaml-quote ${INSTANCE_PREFIX})
 NODE_INSTANCE_PREFIX: $(yaml-quote ${NODE_INSTANCE_PREFIX})
 SERVER_BINARY_TAR_URL: $(yaml-quote ${SERVER_BINARY_TAR_URL})