diff --git a/package/base-files/files/bin/ipcalc.sh b/package/base-files/files/bin/ipcalc.sh
index b21b6e28dc6..e818e678033 100755
--- a/package/base-files/files/bin/ipcalc.sh
+++ b/package/base-files/files/bin/ipcalc.sh
@@ -1,6 +1,5 @@
-#!/bin/sh
+#!/usr/bin/awk -f
 
-awk -f - $* <<EOF
 function bitcount(c) {
 	c=and(rshift(c, 1),0x55555555)+and(c,0x55555555)
 	c=and(rshift(c, 2),0x33333333)+and(c,0x33333333)
@@ -82,4 +81,3 @@ BEGIN {
 	print "START="int2ip(start)
 	print "END="int2ip(end)
 }
-EOF