diff --git a/bin/nim-gdb b/bin/nim-gdb
index f7f9a79c628e2..e802309f8c631 100755
--- a/bin/nim-gdb
+++ b/bin/nim-gdb
@@ -1,4 +1,4 @@
-#!/usr/bin/env bash
+#!/bin/sh
 
 # Exit if anything fails
 set -e
@@ -7,7 +7,7 @@ which nim > /dev/null || (echo "nim not in PATH"; exit 1)
 which gdb > /dev/null || (echo "gdb not in PATH"; exit 1)
 which readlink > /dev/null || (echo "readlink not in PATH."; exit 1)
 
-if [[ "$(uname -s)" == "Darwin" || "(uname -s)" == *"BSD" ]]; then
+if (uname="$(uname -s)"; [ "$uname" = Darwin -o -z "${uname##*BSD}" ]); then
   NIM_SYSROOT=$(dirname $(dirname $(readlink -f $(which nim))))
 else
   NIM_SYSROOT=$(dirname $(dirname $(readlink -e $(which nim))))