diff --git a/tools/sort_symfile.sh b/tools/sort_symfile.sh
index 1b39fbc6f..d53150faa 100755
--- a/tools/sort_symfile.sh
+++ b/tools/sort_symfile.sh
@@ -1,3 +1,4 @@
+#!/bin/sh
 sed $1 \
     -e "s/^..:[0-3]/0_ROM0@&/g" \
     -e "s/^..:[4-7]/1_ROMX@&/g" \