diff --git a/tools/zasm.sh b/tools/zasm.sh
index 574f91b..ca93458 100755
--- a/tools/zasm.sh
+++ b/tools/zasm.sh
@@ -1,7 +1,11 @@
-#!/bin/sh
+#!/usr/bin/env bash
+
+# readlink -f doesn't work with macOS's implementation
+# so, if we can't get readlink -f to work, try python with a realpath implementation
+ABS_PATH=$(readlink -f "$0" || python -c "import sys, os; print(os.path.realpath('$0'))")
 
 # wrapper around ./emul/zasm/zasm that prepares includes CFS prior to call
-DIR=$(dirname $(readlink -f "$0"))
+DIR=$(dirname "${ABS_PATH}")
 ZASMBIN="${DIR}/emul/zasm/zasm"
 CFSPACK="${DIR}/cfspack/cfspack"
 INCCFS=$(mktemp)