diff --git a/doc/TODO b/doc/TODO
index 8e707f4c96..f371d4507f 100644
--- a/doc/TODO
+++ b/doc/TODO
@@ -148,7 +148,7 @@ Rendezvous service:
           protocol, how do we deal? have nodes parse the tor version field?
           force an upgrade? simply be more robust against useless nodes?
         o should expire rend streams when too much time has passed
-        - should make failed rend/intro circs count toward alice's
+        o should make failed rend/intro circs count toward alice's
           num_failed circs, to prevent madness when we're offline (But
           don't count failed rend circs toward Bob's total, or Alice
           can bork him.)
diff --git a/src/common/util.c b/src/common/util.c
index bbe3933b43..935aadea92 100644
--- a/src/common/util.c
+++ b/src/common/util.c
@@ -213,7 +213,13 @@ void smartlist_clear(smartlist_t *sl) {
   sl->num_used = 0;
 }
 
-/* add element to the list, but only if there's room */
+void smartlist_truncate(smartlist_t *sl, int len)
+{
+  assert(len <= sl->num_used);
+  sl->num_used = len;
+}
+
+/* add element to the list */
 void smartlist_add(smartlist_t *sl, void *element) {
   if (sl->num_used >= sl->capacity) {
     sl->capacity *= 2;
@@ -222,6 +228,12 @@ void smartlist_add(smartlist_t *sl, void *element) {
   sl->list[sl->num_used++] = element;
 }
 
+/* Add all elements from S2 to S1. */
+void smartlist_add_all(smartlist_t *sl, const smartlist_t *s2)
+{
+  SMARTLIST_FOREACH(s2, void *, element, smartlist_add(sl, element));
+}
+
 void smartlist_remove(smartlist_t *sl, void *element) {
   int i;
   if(element == NULL)
@@ -233,7 +245,7 @@ void smartlist_remove(smartlist_t *sl, void *element) {
     }
 }
 
-int smartlist_isin(smartlist_t *sl, void *element) {
+int smartlist_isin(const smartlist_t *sl, void *element) {
   int i;
   for(i=0; i < sl->num_used; i++)
     if(sl->list[i] == element)
@@ -241,7 +253,7 @@ int smartlist_isin(smartlist_t *sl, void *element) {
   return 0;
 }
 
-int smartlist_overlap(smartlist_t *sl1, smartlist_t *sl2) {
+int smartlist_overlap(const smartlist_t *sl1, const smartlist_t *sl2) {
   int i;
   for(i=0; i < sl2->num_used; i++)
     if(smartlist_isin(sl1, sl2->list[i]))
@@ -250,7 +262,7 @@ int smartlist_overlap(smartlist_t *sl1, smartlist_t *sl2) {
 }
 
 /* remove elements of sl1 that aren't in sl2 */
-void smartlist_intersect(smartlist_t *sl1, smartlist_t *sl2) {
+void smartlist_intersect(smartlist_t *sl1, const smartlist_t *sl2) {
   int i;
   for(i=0; i < sl1->num_used; i++)
     if(!smartlist_isin(sl2, sl1->list[i])) {
@@ -260,19 +272,19 @@ void smartlist_intersect(smartlist_t *sl1, smartlist_t *sl2) {
 }
 
 /* remove all elements of sl2 from sl1 */
-void smartlist_subtract(smartlist_t *sl1, smartlist_t *sl2) {
+void smartlist_subtract(smartlist_t *sl1, const smartlist_t *sl2) {
   int i;
   for(i=0; i < sl2->num_used; i++)
     smartlist_remove(sl1, sl2->list[i]);
 }
 
-void *smartlist_choose(smartlist_t *sl) {
+void *smartlist_choose(const smartlist_t *sl) {
   if(sl->num_used)
     return sl->list[crypto_pseudo_rand_int(sl->num_used)];
   return NULL; /* no elements to choose from */
 }
 
-void *smartlist_get(smartlist_t *sl, int idx)
+void *smartlist_get(const smartlist_t *sl, int idx)
 {
   assert(sl && idx>=0 && idx < sl->num_used);
   return sl->list[idx];
@@ -303,7 +315,7 @@ void *smartlist_del_keeporder(smartlist_t *sl, int idx)
     memmove(sl->list+idx, sl->list+idx+1, sizeof(void*)*(sl->num_used-idx));
   return old;
 }
-int smartlist_len(smartlist_t *sl)
+int smartlist_len(const smartlist_t *sl)
 {
   return sl->num_used;
 }
diff --git a/src/common/util.h b/src/common/util.h
index 763de87952..73627f714f 100644
--- a/src/common/util.h
+++ b/src/common/util.h
@@ -103,19 +103,21 @@ smartlist_t *smartlist_create();
 void smartlist_free(smartlist_t *sl);
 void smartlist_set_capacity(smartlist_t *sl, int n);
 void smartlist_clear(smartlist_t *sl);
+void smartlist_truncate(smartlist_t *sl, int n);
 void smartlist_add(smartlist_t *sl, void *element);
+void smartlist_add_all(smartlist_t *sl, const smartlist_t *s2);
 void smartlist_remove(smartlist_t *sl, void *element);
-int smartlist_isin(smartlist_t *sl, void *element);
-int smartlist_overlap(smartlist_t *sl1, smartlist_t *sl2);
-void smartlist_intersect(smartlist_t *sl1, smartlist_t *sl2);
-void smartlist_subtract(smartlist_t *sl1, smartlist_t *sl2);
-void *smartlist_choose(smartlist_t *sl);
-void *smartlist_get(smartlist_t *sl, int idx);
+int smartlist_isin(const smartlist_t *sl, void *element);
+int smartlist_overlap(const smartlist_t *sl1, const smartlist_t *sl2);
+void smartlist_intersect(smartlist_t *sl1, const smartlist_t *sl2);
+void smartlist_subtract(smartlist_t *sl1, const smartlist_t *sl2);
+void *smartlist_choose(const smartlist_t *sl);
+void *smartlist_get(const smartlist_t *sl, int idx);
 void *smartlist_set(smartlist_t *sl, int idx, void *val);
 void *smartlist_del(smartlist_t *sl, int idx);
 void *smartlist_del_keeporder(smartlist_t *sl, int idx);
 void smartlist_insert(smartlist_t *sl, int idx, void *val);
-int smartlist_len(smartlist_t *sl);
+int smartlist_len(const smartlist_t *sl);
 #define SMARTLIST_FOREACH(sl, type, var, cmd)                   \
   do {                                                          \
     int sl_idx, sl_len=smartlist_len(sl);                       \
diff --git a/src/or/onion.c b/src/or/onion.c
index d97c397973..8bc9c0a23c 100644
--- a/src/or/onion.c
+++ b/src/or/onion.c
@@ -337,7 +337,16 @@ static routerinfo_t *choose_good_exit_server(uint8_t purpose, routerlist_t *dir)
 {
   if(purpose == CIRCUIT_PURPOSE_C_GENERAL)
     return choose_good_exit_server_general(dir);
-  else
+  else if (purpose == CIRCUIT_PURPOSE_C_ESTABLISH_REND ||
+           purpose == CIRCUIT_PURPOSE_C_REND_JOINED) {
+    smartlist_t *obsolete_routers;
+    routerinfo_t *r;
+    obsolete_routers = smartlist_create();
+    router_add_nonrendezvous_to_list(obsolete_routers);
+    r = router_choose_random_node(dir, options.RendNodes, options.RendExcludeNodes, NULL);
+    smartlist_free(obsolete_routers);
+    return r;
+  } else
     return router_choose_random_node(dir, options.RendNodes, options.RendExcludeNodes, NULL);
 }
 
diff --git a/src/or/or.h b/src/or/or.h
index 0a0b08591f..ed1f3b494b 100644
--- a/src/or/or.h
+++ b/src/or/or.h
@@ -461,6 +461,8 @@ typedef struct {
 
   int is_running;
 
+  char *platform;
+
   /* link info */
   uint32_t bandwidthrate;
   uint32_t bandwidthburst;
@@ -996,6 +998,8 @@ routerinfo_t *router_get_by_link_pk(crypto_pk_env_t *pk);
 routerinfo_t *router_get_by_nickname(char *nickname);
 void router_get_routerlist(routerlist_t **prouterlist);
 void routerinfo_free(routerinfo_t *router);
+int router_version_supports_rendezvous(routerinfo_t *router);
+void router_add_nonrendezvous_to_list(smartlist_t *sl);
 void router_mark_as_down(char *nickname);
 int router_set_routerlist_from_file(char *routerfile);
 int router_set_routerlist_from_string(const char *s);
diff --git a/src/or/rendservice.c b/src/or/rendservice.c
index be7ddcb1ee..2042b6bb4e 100644
--- a/src/or/rendservice.c
+++ b/src/or/rendservice.c
@@ -657,10 +657,14 @@ int rend_services_init(void) {
   rend_service_t *service;
   char *desc, *intro;
   int changed, prev_intro_nodes, desc_len;
-  smartlist_t *intro_routers;
+  smartlist_t *intro_routers, *exclude_routers;
+  int n_old_routers;
 
   router_get_routerlist(&rl);
   intro_routers = smartlist_create();
+  exclude_routers = smartlist_create();
+  router_add_nonrendezvous_to_list(exclude_routers);
+  n_old_routers = smartlist_len(exclude_routers);
 
   for (i=0; i< smartlist_len(rend_service_list); ++i) {
     smartlist_clear(intro_routers);
@@ -688,12 +692,13 @@ int rend_services_init(void) {
     /* Remember how many introduction circuits we started with. */
     prev_intro_nodes = smartlist_len(service->intro_nodes);
 
+    smartlist_add_all(exclude_routers, intro_routers);
     /* The directory is now here. Pick three ORs as intro points. */
     for (j=prev_intro_nodes; j < NUM_INTRO_POINTS; ++j) {
       router = router_choose_random_node(rl,
                                          service->intro_prefer_nodes,
                                          service->intro_exclude_nodes,
-                                         intro_routers);
+                                         exclude_routers);
       if (!router) {
         log_fn(LOG_WARN, "Can't establish more than %d introduction points",
                smartlist_len(service->intro_nodes));
@@ -701,9 +706,14 @@ int rend_services_init(void) {
       }
       changed = 1;
       smartlist_add(intro_routers, router);
+      smartlist_add(exclude_routers, router);
       smartlist_add(service->intro_nodes, tor_strdup(router->nickname));
     }
 
+    /* Reset exclude_routers to include obsolete routers only for the next
+     * time around the loop. */
+    smartlist_truncate(exclude_routers, n_old_routers);
+
     /* If there's no need to republish, stop here. */
     if (!changed)
       continue;
@@ -731,6 +741,7 @@ int rend_services_init(void) {
     }
   }
   smartlist_free(intro_routers);
+  smartlist_free(exclude_routers);
 
   return 0;
 }
diff --git a/src/or/router.c b/src/or/router.c
index ead4162f58..467f1dd2c6 100644
--- a/src/or/router.c
+++ b/src/or/router.c
@@ -6,6 +6,8 @@
 
 extern or_options_t options; /* command-line and config-file options */
 
+static void get_platform_str(char *platform, int len);
+
 /************************************************************/
 
 /* private keys */
@@ -353,6 +355,7 @@ const char *router_get_my_descriptor(void) {
 int router_rebuild_descriptor(void) {
   routerinfo_t *ri;
   struct in_addr addr;
+  char platform[256];
   if (!tor_inet_aton(options.Address, &addr)) {
     log_fn(LOG_ERR, "options.Address didn't hold an IP.");
     return -1;
@@ -369,6 +372,8 @@ int router_rebuild_descriptor(void) {
   ri->onion_pkey = crypto_pk_dup_key(get_onion_key());
   ri->link_pkey = crypto_pk_dup_key(get_link_key());
   ri->identity_pkey = crypto_pk_dup_key(get_identity_key());
+  get_platform_str(platform, sizeof(platform));
+  ri->platform = tor_strdup(platform);
   ri->bandwidthrate = options.BandwidthRate;
   ri->bandwidthburst = options.BandwidthBurst;
   ri->exit_policy = NULL; /* zero it out first */
@@ -401,7 +406,6 @@ int router_dump_router_to_string(char *s, int maxlen, routerinfo_t *router,
   char *link_pkey;
   char *identity_pkey;
   struct in_addr in;
-  char platform[256];
   char digest[20];
   char signature[128];
   char published[32];
@@ -415,8 +419,6 @@ int router_dump_router_to_string(char *s, int maxlen, routerinfo_t *router,
   routerinfo_t *ri_tmp;
 #endif
 
-  get_platform_str(platform, sizeof(platform));
-
   if (crypto_pk_cmp_keys(ident_key, router->identity_pkey)) {
     log_fn(LOG_WARN,"Tried to sign a router with a private key that didn't match router's public key!");
     return -1;
@@ -455,7 +457,7 @@ int router_dump_router_to_string(char *s, int maxlen, routerinfo_t *router,
     router->dir_port,
     (int) router->bandwidthrate,
 /* XXXBC also write bandwidthburst */
-    platform,
+    router->platform,
     published,
     onion_pkey, link_pkey, identity_pkey);
 
diff --git a/src/or/routerlist.c b/src/or/routerlist.c
index d37e5542b3..088ad3c921 100644
--- a/src/or/routerlist.c
+++ b/src/or/routerlist.c
@@ -236,6 +236,24 @@ void router_add_running_routers_to_smartlist(smartlist_t *sl) {
   }
 }
 
+/* Return 0 if router is running a version of Tor too old to be a
+ * rendezvous/introduction point.  Return 1 otherwise.
+ */
+int router_version_supports_rendezvous(routerinfo_t *router)
+{
+  return (router->platform && 0==strncasecmp(router->platform,"Tor 0.0.5",9));
+}
+
+/* Add every router running a version of Tor too old for rend/intro
+   points to sl.
+ */
+void router_add_nonrendezvous_to_list(smartlist_t *sl)
+{
+  SMARTLIST_FOREACH(routerlist->routers, routerinfo_t *, r,
+                    if (!router_version_supports_rendezvous(r))
+                      smartlist_add(sl,r));
+}
+
 /* Pick a random node from preferred if possible, else from all of dir.
  * Never pick a node in excluded.
  * If excludedsmartlist is defined, never pick a node in it either.
@@ -333,6 +351,7 @@ void routerinfo_free(routerinfo_t *router)
 
   tor_free(router->address);
   tor_free(router->nickname);
+  tor_free(router->platform);
   if (router->onion_pkey)
     crypto_free_pk_env(router->onion_pkey);
   if (router->link_pkey)
@@ -988,6 +1007,10 @@ routerinfo_t *router_get_entry_from_string(const char *s,
   router->identity_pkey = tok->key;
   tok->key = NULL; /* Prevent free */
 
+  if ((tok = find_first_by_keyword(tokens, K_PLATFORM))) {
+    router->platform = tor_strdup(tok->args[0]);
+  }
+
   exit_policy_tokens = find_all_exitpolicy(tokens);
   SMARTLIST_FOREACH(exit_policy_tokens, directory_token_t *, t,
                     if (router_add_exit_policy(router,t)<0) {
@@ -1023,6 +1046,9 @@ routerinfo_t *router_get_entry_from_string(const char *s,
     log_fn(LOG_WARN,"bandwidthrate unreadable or 0. Failing.");
     goto err;
   }
+  if (!router->platform) {
+    router->platform = tor_strdup("<unknown>");
+  }
 
 #if XXXBC
   router->bandwidthburst = atoi(ARGS[6]);