diff --git a/trisquel-automatic-netinstall-qemu/configure.ac b/trisquel-automatic-netinstall-qemu/configure.ac
index f78db59..f9648c8 100644
--- a/trisquel-automatic-netinstall-qemu/configure.ac
+++ b/trisquel-automatic-netinstall-qemu/configure.ac
@@ -52,7 +52,7 @@ AC_ARG_WITH(
 AC_ARG_WITH(
   [--with-trisquel-target-rootfs-size],
   [AS_HELP_STRING(
-    [--trisquel-target-rootfs-size=SIZE],
+    [--with-trisquel-target-rootfs-size=SIZE],
     [Size of the target image (default=3.5G). The size will be passed
     as-is to the 'qemu-img create' command. See 'man 1 qemu-img' for
     more details.])],