diff --git a/bin/brew b/bin/brew
index 294091fe81..faa1fad88d 100755
--- a/bin/brew
+++ b/bin/brew
@@ -1,4 +1,4 @@
-#!/bin/bash -p
+#!/bin/bash -pu
 set -u
 
 # Fail fast with concise message when not using bash