diff --git a/home/roles/aerospace/default.nix b/home/roles/aerospace/default.nix
index 43a592d..f7253ba 100644
--- a/home/roles/aerospace/default.nix
+++ b/home/roles/aerospace/default.nix
@@ -632,8 +632,9 @@ in
       text = ''
         #!/bin/bash
 
-        # df $5 can show free% on some APFS setups; calculate used% explicitly
-        DISK_USAGE=$(df -H / | grep -v Filesystem | awk '{gsub(/%/,"",$5); printf "%.0f%%", 100-$5}')
+        # Monitor /System/Volumes/Data which contains user data on APFS
+        # The root / is a read-only snapshot with minimal usage
+        DISK_USAGE=$(df -H /System/Volumes/Data | grep -v Filesystem | awk '{print $5}')
 
         ${pkgs.sketchybar}/bin/sketchybar --set $NAME label="$DISK_USAGE"
       '';