diff --git a/backup.nix b/backup.nix
index bd5cc21..9909f46 100644
--- a/backup.nix
+++ b/backup.nix
@@ -14,8 +14,7 @@ let
       exit_code=0;
       for i in ''${BACKUP_HELPER_DIRS//,/ }; do
         echo "Starting backup of $i";
-        output=$(restic backup "$i");
-        if [ "$?" -ne 0 ]; then
+        if ! output=$(restic backup "$i"); then
           exit_code="$?";
           echo "Backup of $i failed with exit code $?:"
           echo "$output"