diff --git a/code/2025-09-03-progress-bar-2/progress-bar b/code/2025-09-03-progress-bar-2/progress-bar
index 1f002c1..6f5ba27 100755
--- a/code/2025-09-03-progress-bar-2/progress-bar
+++ b/code/2025-09-03-progress-bar-2/progress-bar
@@ -12,6 +12,8 @@ fatal() {
 progress-bar() {
 	local current=$1
 	local len=$2
+    # if len is zero, fail gracefully
+    [ ! "$len" ]||[ "$len" -le 0 ]&& return
 
 	local perc_done=$((current * 100 / len))