diff --git a/cluster/get-kube-binaries.sh b/cluster/get-kube-binaries.sh
index 435decd9be9..251b8f49d6e 100755
--- a/cluster/get-kube-binaries.sh
+++ b/cluster/get-kube-binaries.sh
@@ -164,8 +164,8 @@ SERVER_PLATFORM="linux"
 SERVER_ARCH="${KUBERNETES_SERVER_ARCH:-amd64}"
 SERVER_TAR="kubernetes-server-${SERVER_PLATFORM}-${SERVER_ARCH}.tar.gz"
 if [[ -n "${KUBERNETES_NODE_PLATFORM-}" || -n "${KUBERNETES_NODE_ARCH-}" ]]; then
-  NODE_PLATFORM="${KUBERNETES_NODE_PLATFORM:${SERVER_PLATFORM}}"
-  NODE_ARCH="${KUBERNETES_NODE_ARCH:${SERVER_ARCH}}"
+  NODE_PLATFORM="${KUBERNETES_NODE_PLATFORM:-${SERVER_PLATFORM}}"
+  NODE_ARCH="${KUBERNETES_NODE_ARCH:-${SERVER_ARCH}}"
   NODE_TAR="kubernetes-node-${NODE_PLATFORM}-${NODE_ARCH}.tar.gz"
 fi