diff --git a/build/lib/release.sh b/build/lib/release.sh
index 069c35613ce9c..6d23dc2033986 100644
--- a/build/lib/release.sh
+++ b/build/lib/release.sh
@@ -108,7 +108,7 @@ function kube::release::package_tarballs() {
 function kube::release::package_src_tarball() {
   local -r src_tarball="${RELEASE_TARS}/kubernetes-src.tar.gz"
   kube::log::status "Building tarball: src"
-  if [ "${KUBE_GIT_TREE_STATE-}" = 'clean' ]; then
+  if [[ "${KUBE_GIT_TREE_STATE-}" = 'clean' ]]; then
     git archive -o "${src_tarball}" HEAD
   else
     find "${KUBE_ROOT}" -mindepth 1 -maxdepth 1 \
@@ -140,7 +140,7 @@ function kube::release::package_client_tarballs() {
       mkdir -p "${release_stage}/client/bin"
 
       local client_bins=("${KUBE_CLIENT_BINARIES[@]}")
-      if [ "${platform%/*}" = 'windows' ]; then
+      if [[ "${platform%/*}" = 'windows' ]]; then
         client_bins=("${KUBE_CLIENT_BINARIES_WIN[@]}")
       fi
 
@@ -176,7 +176,7 @@ function kube::release::package_node_tarballs() {
     mkdir -p "${release_stage}/node/bin"
 
     local node_bins=("${KUBE_NODE_BINARIES[@]}")
-    if [ "${platform%/*}" = 'windows' ]; then
+    if [[ "${platform%/*}" = 'windows' ]]; then
       node_bins=("${KUBE_NODE_BINARIES_WIN[@]}")
     fi
     # This fancy expression will expand to prepend a path
@@ -190,7 +190,7 @@ function kube::release::package_node_tarballs() {
 
     # Include the client binaries here too as they are useful debugging tools.
     local client_bins=("${KUBE_CLIENT_BINARIES[@]}")
-    if [ "${platform%/*}" = 'windows' ]; then
+    if [[ "${platform%/*}" = 'windows' ]]; then
       client_bins=("${KUBE_CLIENT_BINARIES_WIN[@]}")
     fi
     # This fancy expression will expand to prepend a path
@@ -262,7 +262,7 @@ function kube::release::package_server_tarballs() {
     # Include the client binaries here too as they are useful debugging tools.
     local client_bins
     client_bins=("${KUBE_CLIENT_BINARIES[@]}")
-    if [ "${platform%/*}" = 'windows' ]; then
+    if [[ "${platform%/*}" = 'windows' ]]; then
       client_bins=("${KUBE_CLIENT_BINARIES_WIN[@]}")
     fi
     # This fancy expression will expand to prepend a path
@@ -310,7 +310,7 @@ function kube::release::build_hyperkube_image() {
 
   local hyperkube_tag
   hyperkube_tag="${registry}/hyperkube-${arch}:${version}"
-  if [ -n "${save_dir}" ]; then
+  if [[ -n "${save_dir}" ]]; then
     "${DOCKER[@]}" save "${hyperkube_tag}" > "${save_dir}/hyperkube-${arch}.tar"
   fi
   kube::log::status "Deleting hyperkube image ${hyperkube_tag}"
@@ -328,7 +328,7 @@ function kube::release::build_conformance_image() {
 
   local conformance_tag
   conformance_tag="${registry}/conformance-${arch}:${version}"
-  if [ -n "${save_dir}" ]; then
+  if [[ -n "${save_dir}" ]]; then
     "${DOCKER[@]}" save "${conformance_tag}" > "${save_dir}/conformance-${arch}.tar"
   fi
   kube::log::status "Deleting conformance image ${conformance_tag}"
@@ -358,7 +358,7 @@ function kube::release::create_docker_images_for_server() {
     local -r docker_registry="k8s.gcr.io"
     # Docker tags cannot contain '+'
     local docker_tag="${KUBE_GIT_VERSION/+/_}"
-    if [ -z "${docker_tag}" ]; then
+    if [[ -z "${docker_tag}" ]]; then
       kube::log::error "git version information missing; cannot create Docker tag"
       return 1
     fi
@@ -401,7 +401,7 @@ EOF
         # If we are building an official/alpha/beta release we want to keep
         # docker images and tag them appropriately.
         local -r release_docker_image_tag="${KUBE_DOCKER_REGISTRY-$docker_registry}/${binary_name}-${arch}:${KUBE_DOCKER_IMAGE_TAG-$docker_tag}"
-        if [ "${release_docker_image_tag}" != "${docker_image_tag}" ]; then
+        if [[ "${release_docker_image_tag}" != "${docker_image_tag}" ]]; then
           kube::log::status "Tagging docker image ${docker_image_tag} as ${release_docker_image_tag}"
           "${DOCKER[@]}" rmi "${release_docker_image_tag}" 2>/dev/null || true
           "${DOCKER[@]}" tag "${docker_image_tag}" "${release_docker_image_tag}" 2>/dev/null
@@ -456,7 +456,7 @@ function kube::release::package_kube_manifests_tarball() {
   find "${src_dir}" -name 'internal-*' -exec cp {} "${dst_dir}" \;
   cp "${KUBE_ROOT}/cluster/gce/gci/configure-helper.sh" "${dst_dir}/gci-configure-helper.sh"
   cp "${KUBE_ROOT}/cluster/gce/gci/configure-kubeapiserver.sh" "${dst_dir}/configure-kubeapiserver.sh"
-  if [ -e "${KUBE_ROOT}/cluster/gce/gci/gke-internal-configure-helper.sh" ]; then
+  if [[ -e "${KUBE_ROOT}/cluster/gce/gci/gke-internal-configure-helper.sh" ]]; then
     cp "${KUBE_ROOT}/cluster/gce/gci/gke-internal-configure-helper.sh" "${dst_dir}/"
   fi
   cp "${KUBE_ROOT}/cluster/gce/gci/health-monitor.sh" "${dst_dir}/health-monitor.sh"
@@ -495,7 +495,7 @@ function kube::release::package_test_platform_tarballs() {
       mkdir -p "${release_stage}/test/bin"
 
       local test_bins=("${KUBE_TEST_BINARIES[@]}")
-      if [ "${platform%/*}" = 'windows' ]; then
+      if [[ "${platform%/*}" = 'windows' ]]; then
         test_bins=("${KUBE_TEST_BINARIES_WIN[@]}")
       fi
       # This fancy expression will expand to prepend a path