Index: l4/pkg/sigma0/server/src/ioports_x86.cc
===================================================================
--- l4/pkg/sigma0/server/src/ioports_x86.cc	(revision 40)
+++ l4/pkg/sigma0/server/src/ioports_x86.cc	(working copy)
@@ -39,8 +39,9 @@
   size = l4_fpage_size(fp) + PORT_SHIFT;
 
   unsigned long i = io_ports.alloc(Region::bs(port, 1UL << size, t));
-  if (i == port)
+  if (i == port) {
     a->snd_fpage(l4_iofpage(port >> PORT_SHIFT, size - PORT_SHIFT));
-  else
+    a->tag = l4_msgtag(0, 0, 1, 0);
+  } else
     a->error(L4_ENOMEM);
 }