diff --git a/hack/setup-kubebuilder-env.sh b/hack/setup-kubebuilder-env.sh
index 04e578164..e089e71eb 100755
--- a/hack/setup-kubebuilder-env.sh
+++ b/hack/setup-kubebuilder-env.sh
@@ -5,6 +5,6 @@
 SHELL="/usr/bin/env bash -o pipefail"
 
 ENVTEST_ASSETS_DIR=$(pwd)/testbin
-mkdir -p ${ENVTEST_ASSETS_DIR}
-test -f ${ENVTEST_ASSETS_DIR}/setup-envtest.sh || curl -sSLo ${ENVTEST_ASSETS_DIR}/setup-envtest.sh https://raw.githubusercontent.com/kubernetes-sigs/controller-runtime/v0.8.3/hack/setup-envtest.sh
-source ${ENVTEST_ASSETS_DIR}/setup-envtest.sh; fetch_envtest_tools ${ENVTEST_ASSETS_DIR}; setup_envtest_env ${ENVTEST_ASSETS_DIR}
+mkdir -p "${ENVTEST_ASSETS_DIR}"
+test -f "${ENVTEST_ASSETS_DIR}"/setup-envtest.sh || curl -sSLo "${ENVTEST_ASSETS_DIR}"/setup-envtest.sh https://raw.githubusercontent.com/kubernetes-sigs/controller-runtime/v0.8.3/hack/setup-envtest.sh
+source "${ENVTEST_ASSETS_DIR}"/setup-envtest.sh; fetch_envtest_tools "${ENVTEST_ASSETS_DIR}"; setup_envtest_env "${ENVTEST_ASSETS_DIR}"