-MAJOR=$(echo __GNUC__ | $compiler -E -xc - | tail -n 1)
-MINOR=$(echo __GNUC_MINOR__ | $compiler -E -xc - | tail -n 1)
+if [ ${#compiler} -eq 0 ]; then
+ echo "Error: No compiler specified."
+ printf "Usage:\n\t$0 <gcc-command>\n"
+ exit 1
+fi
+
+MAJOR=$(echo __GNUC__ | $compiler -E -x c - | tail -n 1)
+MINOR=$(echo __GNUC_MINOR__ | $compiler -E -x c - | tail -n 1)