diff --git a/13/02.sh b/13/02.sh
index 4a62b1e..301d691 100755
--- a/13/02.sh
+++ b/13/02.sh
@@ -50,8 +50,8 @@ for fold in ${folds[@]}; do
   done
 done
 
-for j in $(seq 0 $min_y); do
-  for i in $(seq 0 $min_x); do
+for ((j=0; j<$min_y; j++)); do
+  for ((i=0; i<$min_x; i++)); do
     if [ ${dots["$i,$j"]} ]; then
       echo -n '█'
     else