diff --git a/cluster/common.sh b/cluster/common.sh
index 00f00f1706..80e7ec12a4 100755
--- a/cluster/common.sh
+++ b/cluster/common.sh
@@ -369,6 +369,13 @@ function set_binary_version() {
 #   SALT_TAR_URL
 #   SALT_TAR_HASH
 function tars_from_version() {
+  local sha1sum=""
+  if which sha1sum >/dev/null 2>&1; then
+    sha1sum="sha1sum"
+  else
+    sha1sum="shasum -a1"
+  fi
+
   if [[ -z "${KUBE_VERSION-}" ]]; then
     find-release-tars
     upload-server-tars
@@ -377,13 +384,13 @@ function tars_from_version() {
     SALT_TAR_URL="https://storage.googleapis.com/kubernetes-release/release/${KUBE_VERSION}/kubernetes-salt.tar.gz"
     # TODO: Clean this up.
     KUBE_MANIFESTS_TAR_URL="${SERVER_BINARY_TAR_URL/server-linux-amd64/manifests}"
-    KUBE_MANIFESTS_TAR_HASH=$(curl ${KUBE_MANIFESTS_TAR_URL} --silent --show-error | sha1sum | awk '{print $1}')
+    KUBE_MANIFESTS_TAR_HASH=$(curl ${KUBE_MANIFESTS_TAR_URL} --silent --show-error | ${sha1sum} | awk '{print $1}')
   elif [[ ${KUBE_VERSION} =~ ${KUBE_CI_VERSION_REGEX} ]]; then
     SERVER_BINARY_TAR_URL="https://storage.googleapis.com/kubernetes-release-dev/ci/${KUBE_VERSION}/kubernetes-server-linux-amd64.tar.gz"
     SALT_TAR_URL="https://storage.googleapis.com/kubernetes-release-dev/ci/${KUBE_VERSION}/kubernetes-salt.tar.gz"
     # TODO: Clean this up.
     KUBE_MANIFESTS_TAR_URL="${SERVER_BINARY_TAR_URL/server-linux-amd64/manifests}"
-    KUBE_MANIFESTS_TAR_HASH=$(curl ${KUBE_MANIFESTS_TAR_URL} --silent --show-error | sha1sum | awk '{print $1}')
+    KUBE_MANIFESTS_TAR_HASH=$(curl ${KUBE_MANIFESTS_TAR_URL} --silent --show-error | ${sha1sum} | awk '{print $1}')
   else
     echo "Version doesn't match regexp" >&2
     exit 1