diff --git a/usr/bin/unzip_bruteforce b/usr/bin/unzip_bruteforce
index 050c09c..8e33f57 100755
--- a/usr/bin/unzip_bruteforce
+++ b/usr/bin/unzip_bruteforce
@@ -1,27 +1,32 @@
-#!/usr/bin/bash
+#!/usr/bin/env bash
 
-if [ "$#" -lt 1 ] || [ "$#" -gt 3 ]; then
-    echo "Usage: $0 list file.zip"
+set -euo pipefail
+
+LIST=${1:-list}
+FILE=${2:-}
+
+usage() {
+    echo "usage: $0 [wordlist] <zipfile>"
+    echo "default wordlist: ./list"
     exit 1
-fi
+}
 
-LIST=$1
-FILE=$2
-COUNT=$(mktemp)
-echo 0 > "$COUNT"
-export FILE COUNT
+[[ -z "$FILE" ]] && usage
+[[ ! -f "$LIST" ]] && { echo "missing wordlist: $LIST"; exit 1; }
+[[ ! -f "$FILE" ]] && { echo "missing zip: $FILE"; exit 1; }
 
-xargs -a "$LIST" -P4 -I{} bash -c '
-    line="$1"
+i=0
 
-    # atomic-ish counter
-    n=$(($(<"$COUNT")+1))
-    echo "$n" > "$COUNT"
+while IFS= read -r line; do
+    ((i++))
 
-    ((n % 1000 == 0)) && echo "$n tries..."
+    (( i % 1000 == 0 )) && echo "$i tried..."
 
     if unzip -P "$line" -t "$FILE" >/dev/null 2>&1; then
         echo "FOUND: $line"
-        killall xargs 2>/dev/null
+        exit 0
     fi
-' _ {}
+done < "$LIST"
+
+echo "not found"
+exit 1