diff --git a/bin/apple-display-brightness b/bin/apple-display-brightness
index 8d091f8..e611e8b 100755
--- a/bin/apple-display-brightness
+++ b/bin/apple-display-brightness
@@ -1,6 +1,6 @@
 #!/bin/bash
 
-if [[ -z "$1" ]]; then
+if [[ $# -eq 0 ]]; then
   echo "Adjust Apple Display Brightness by passing +5000 or -5000 (or any range from 0-60000)"
 else
   sudo asdcontrol $(sudo asdcontrol --detect /dev/usb/hiddev* | grep ^/dev/usb/hiddev | cut -d: -f1) -- "$1"