diff --git a/config.sub b/config.sub
index ff0323b..2530021 100755
--- a/config.sub
+++ b/config.sub
@@ -344,7 +344,7 @@ case $basic_machine in
 		    -ns2*)
 			;;
 		    *)
-		      $os=-ns3
+		      os=-ns3
 			;;
 		esac
 		;;