diff --git a/cli.sh b/cli.sh
index dd81fad..1571935 100755
--- a/cli.sh
+++ b/cli.sh
@@ -1,4 +1,5 @@
 #!/usr/bin/env bash
+set -u
 
 # Simple CLI wrapper that discovers scripts in the commands/ directory
 
diff --git a/tests/test-cli.sh b/tests/test-cli.sh
index 2dbe2f0..9e7889c 100755
--- a/tests/test-cli.sh
+++ b/tests/test-cli.sh
@@ -1,5 +1,5 @@
 #!/usr/bin/env bash
-set -e
+set -eu
 
 # Cd to the directory of this script
 cd "${0%/*}"