diff --git a/sys/tools/bus_macro.sh b/sys/tools/bus_macro.sh
--- a/sys/tools/bus_macro.sh
+++ b/sys/tools/bus_macro.sh
@@ -34,16 +34,16 @@

        n=${1}
        shift
-       echo -n "#define bus_${n}(r"
+       printf "#define bus_%s(r" "${n}"
        for i
        do
-               echo -n ", ${i}"
+               printf ", %s" "${i}"
        done
        echo ") \\"
-       echo -n "       bus_space_${n}((r)->r_bustag, (r)->r_bushandle"
+       printf "        bus_space_%s((r)->r_bustag, (r)->r_bushandle" "${n}"
        for i
        do
-               echo -n ", (${i})"
+               printf ", (%s)" "${i}"
        done
        echo ")"
 }