diff --git a/ffbuild/libversion.sh b/ffbuild/libversion.sh
index 990ce9f640..30046b1d25 100755
--- a/ffbuild/libversion.sh
+++ b/ffbuild/libversion.sh
@@ -1,3 +1,5 @@
+#!/bin/sh
+
 toupper(){
     echo "$@" | tr abcdefghijklmnopqrstuvwxyz ABCDEFGHIJKLMNOPQRSTUVWXYZ
 }