diff --git a/isisd/ChangeLog b/isisd/ChangeLog
index d7fadd0..6f4f395 100644
--- a/isisd/ChangeLog
+++ b/isisd/ChangeLog
@@ -1,3 +1,10 @@
+2005-04-02 Andrew J. Schorr <ajschorr@alumni.princeton.edu>
+
+	* isis_zebra.c: (isis_zebra_if_del) Call if_delete_retain instead
+	  of if_delete, since it is generally not safe to remove interface
+	  structures.  After deleting, set ifp->ifindex to IFINDEX_INTERNAL.
+	  (zebra_interface_if_lookup) Tighten up code.
+
 2005-03-07 Michael Sandee <voidptr@voidptr.sboost.org>
 
 	* isis_spf.c: host.name might be NULL.
diff --git a/isisd/isis_zebra.c b/isisd/isis_zebra.c
index 40743b2..0f8d116 100644
--- a/isisd/isis_zebra.c
+++ b/isisd/isis_zebra.c
@@ -95,30 +95,28 @@
   zlog_debug ("Zebra I/F delete: %s index %d flags %ld metric %d mtu %d",
 	      ifp->name, ifp->ifindex, ifp->flags, ifp->metric, ifp->mtu);
 
-  if_delete (ifp);
+
+  /* Cannot call if_delete because we should retain the pseudo interface
+     in case there is configuration info attached to it. */
+  if_delete_retain(ifp);
 
   isis_csm_state_change (IF_DOWN_FROM_Z, circuit_scan_by_ifp (ifp), ifp);
 
+  ifp->ifindex = IFINDEX_INTERNAL;
+
   return 0;
 }
 
 static struct interface *
 zebra_interface_if_lookup (struct stream *s)
 {
-  struct interface *ifp;
   u_char ifname_tmp[INTERFACE_NAMSIZ];
 
   /* Read interface name. */
   stream_get (ifname_tmp, s, INTERFACE_NAMSIZ);
 
-  /* Lookup this by interface index. */
-  ifp = if_lookup_by_name ((char *) ifname_tmp);
-
-  /* If such interface does not exist, indicate an error */
-  if (!ifp)
-    return NULL;
-
-  return ifp;
+  /* And look it up. */
+  return if_lookup_by_name ((char *) ifname_tmp);
 }
 
 static int