diff --git a/trisquel-automatic-netinstall-qemu/configure.ac b/trisquel-automatic-netinstall-qemu/configure.ac
index f9648c8..f2e00d1 100644
--- a/trisquel-automatic-netinstall-qemu/configure.ac
+++ b/trisquel-automatic-netinstall-qemu/configure.ac
@@ -50,7 +50,7 @@ AC_ARG_WITH(
   [MIRROR_HTTP_PROXY=])
 
 AC_ARG_WITH(
-  [--with-trisquel-target-rootfs-size],
+  [trisquel-target-rootfs-size],
   [AS_HELP_STRING(
     [--with-trisquel-target-rootfs-size=SIZE],
     [Size of the target image (default=3.5G). The size will be passed