diff --git a/hack/verify-codegen.sh b/hack/verify-codegen.sh
index 6b7f1dcc71a..cb5eaec03a7 100755
--- a/hack/verify-codegen.sh
+++ b/hack/verify-codegen.sh
@@ -22,7 +22,7 @@ export GO111MODULE=on
 
 source $(dirname $0)/../vendor/knative.dev/hack/library.sh
 
-readonly TMP_DIFFROOT="$(mktemp -d ${REPO_ROOT_DIR}/tmpdiffroot.XXXXXX)"
+readonly TMP_DIFFROOT="$(mktemp -d "${REPO_ROOT_DIR}/tmpdiffroot.XXXXXX")"
 
 cleanup() {
   rm -rf "${TMP_DIFFROOT}"