diff --git a/hack/update-codegen.sh b/hack/update-codegen.sh
index 2b2c1672..e8f6afe0 100755
--- a/hack/update-codegen.sh
+++ b/hack/update-codegen.sh
@@ -14,9 +14,10 @@ function codegen() {
     if [[ ${IN_DOCKER:-0} -eq 1 ]]; then
         # Already in a container ($CODEGEN_IMAGE).
         mkdir -p "$(dirname /go/src/$BASE_PKG/$PKG)"
-        ln -sf "$ROOT" "/go/src/$BASE_PKG/$PKG"
+        test -e "/go/src/$BASE_PKG/$PKG" || ln -s "$ROOT" "/go/src/$BASE_PKG/$PKG"
         cd "/go/src/$BASE_PKG/$PKG"
-        /codegen/entrypoint.sh "$@" 2>&1 | sed "s|^|$1 ($PKG) > |"
+        /codegen/entrypoint.sh "$@" 2>&1 \
+          | sed "s|^|$1 ($PKG) > |"
     else
         # Local workstation.
         docker run \