diff --git a/tests/blackbox-segfault.sh b/tests/blackbox-segfault.sh
index 698656b..eebfafc 100755
--- a/tests/blackbox-segfault.sh
+++ b/tests/blackbox-segfault.sh
@@ -1,18 +1,18 @@
-#!/bin/bash
+#!/bin/sh
 #
 # create a normal blackbox
 rm -f crash-test-dummy.fdata
 ./crash_test_dummy
 
 . ./test.conf
 
-for ((i=0; i<$NUM_BB_TESTS; i++))
+for i in $(seq $NUM_BB_TESTS)
 do
     rm -f butchered_blackbox.fdata
     echo " ==== Corrupt blackbox test $i/$NUM_BB_TESTS ===="
     ./file_change_bytes -i crash-test-dummy.fdata -o butchered_blackbox.fdata -n 1024
     ../tools/qb-blackbox butchered_blackbox.fdata
     [ $? -gt 127 ] && exit 1 || true
 done
 
 exit 0