diff --git a/shell/zsh/update b/shell/zsh/update
index e57f20c6..68bf7d7a 100755
--- a/shell/zsh/update
+++ b/shell/zsh/update
@@ -1 +1,5 @@
-is-callable zgen && zgen update
+#!/usr/bin/env bash
+if command -v zgen >/dev/null; then
+    zgen selfupdate
+    zgen update
+fi