diff --git a/HP-15C.tcl b/HP-15C.tcl
index 209392b..2990af9 100755
--- a/HP-15C.tcl
+++ b/HP-15C.tcl
@@ -1,3 +1,9 @@
+#!/bin/sh
+# the next line restarts using wish \
+TCLLIBPATH="/usr/lib/hp15c/lib" exec wish "$0" "$@"
+
+# ----------------- Make script executable, see https://www.tcl.tk/man/tcl8.3/UserCmd/wish.htm
+
 # ------------------------------------------------------------------------------
 #
 #                      H E W L E T T - P A C K A R D  15C