diff --git a/telegram-purple.c b/telegram-purple.c
index 6539f58..2c36508 100644
--- a/telegram-purple.c
+++ b/telegram-purple.c
@@ -226,6 +226,9 @@ static void update_chat_handler (struct tgl_state *TLS, struct tgl_chat *chat, u
 }
 
 static void update_user_typing (struct tgl_state *TLS, struct tgl_user *U, enum tgl_typing_status status) {
+  
+  g_return_if_fail (tgp_blist_peer_get_purple_name (TLS, U->id));
+  
   if (status == tgl_typing_typing) {
     serv_got_typing (tg_get_conn(TLS), tgp_blist_peer_get_purple_name (TLS, U->id), 2, PURPLE_TYPING);
   }
diff --git a/tgp-2prpl.c b/tgp-2prpl.c
index 6797617..5f96407 100644
--- a/tgp-2prpl.c
+++ b/tgp-2prpl.c
@@ -163,7 +163,12 @@ tgl_chat_id_t p2tgl_chat_get_id (PurpleChat *PC) {
 
 void p2tgl_conv_add_user (struct tgl_state *TLS, PurpleConversation *conv,
                           int user, char *message, int flags, int new_arrival) {
-  purple_conv_chat_add_user (purple_conversation_get_chat_data (conv), tgp_blist_peer_get_purple_name (TLS, TGL_MK_USER (user)), message, flags, new_arrival);
+  
+  const char *name = tgp_blist_peer_get_purple_name (TLS, TGL_MK_USER (user));
+  
+  g_return_if_fail (name);
+  
+  purple_conv_chat_add_user (purple_conversation_get_chat_data (conv), name, message, flags, new_arrival);
 }
 
 PurpleNotifyUserInfo *p2tgl_notify_user_info_new (struct tgl_user *U) {
diff --git a/tgp-blist.c b/tgp-blist.c
index 02acf0d..a8e049a 100644
--- a/tgp-blist.c
+++ b/tgp-blist.c
@@ -27,16 +27,14 @@
 const char *tgp_blist_peer_get_purple_name (struct tgl_state *TLS, tgl_peer_id_t id) {
   const char *name = g_hash_table_lookup (tg_get_data (TLS)->id_to_purple_name, GINT_TO_POINTER(tgl_get_peer_id (id)));
   if (! name) {
-    assert (0);
+    g_warn_if_reached();
     return NULL;
   }
   return name;
 }
 
 void tgp_blist_peer_add_purple_name (struct tgl_state *TLS, tgl_peer_id_t id, const char *purple_name) {
-  assert (g_hash_table_lookup (tg_get_data (TLS)->id_to_purple_name, GINT_TO_POINTER(tgl_get_peer_id (id))) == NULL);
-  g_hash_table_insert (tg_get_data (TLS)->id_to_purple_name, GINT_TO_POINTER(tgl_get_peer_id (id)),
-                       g_strdup (purple_name));
+  g_hash_table_replace (tg_get_data (TLS)->id_to_purple_name, GINT_TO_POINTER(tgl_get_peer_id (id)), g_strdup (purple_name));
 }
 
 tgl_peer_t *tgp_blist_peer_find (struct tgl_state *TLS, const char *purple_name) {
diff --git a/tgp-chat.c b/tgp-chat.c
index bd1a245..0073d0a 100644
--- a/tgp-chat.c
+++ b/tgp-chat.c
@@ -88,7 +88,12 @@ static void tgp_chat_add_all_users (struct tgl_state *TLS, PurpleConversation *c
   int i = 0;
   for (; i < C->user_list_size; i++) {
     struct tgl_chat_user *uid = (C->user_list + i);
-    users = g_list_append (users, g_strdup (tgp_blist_peer_get_purple_name (TLS, TGL_MK_USER(uid->user_id))));
+    const char *name = tgp_blist_peer_get_purple_name (TLS, TGL_MK_USER(uid->user_id));
+    if (! name) {
+      g_warn_if_reached();
+      continue;
+    }
+    users = g_list_append (users, g_strdup (name));
     flags = g_list_append (flags, GINT_TO_POINTER(C->admin_id == uid->user_id ? PURPLE_CBFLAGS_FOUNDER : PURPLE_CBFLAGS_NONE));
   }
   purple_conv_chat_add_users (PURPLE_CONV_CHAT(conv), users, NULL, flags, FALSE);
diff --git a/tgp-ft.c b/tgp-ft.c
index 05cbfce..8b064f6 100644
--- a/tgp-ft.c
+++ b/tgp-ft.c
@@ -271,8 +271,11 @@ static PurpleXfer *tgprpl_new_xfer_recv (PurpleConnection * gc, const char *who)
   return X;
 }
 
-void tgprpl_recv_file (PurpleConnection * gc, const char *who, struct tgl_message *M) {
+void tgprpl_recv_file (PurpleConnection *gc, const char *who, struct tgl_message *M) {
   debug ("tgprpl_recv_file()");
+  
+  g_return_if_fail (who);
+  
   PurpleXfer *X = tgprpl_new_xfer_recv (gc, who);
   const char *mime_type, *caption;
   long long access_hash;
diff --git a/tgp-msg.c b/tgp-msg.c
index 450827a..77ea40a 100644
--- a/tgp-msg.c
+++ b/tgp-msg.c
@@ -101,10 +101,13 @@ static char *format_service_msg (struct tgl_state *TLS, struct tgl_message *M) {
         PurpleConversation *conv = tgp_chat_show (TLS, &chatPeer->chat);
         if (conv) {
           char *alias = peer->print_name;
+          const char *aliasLeft = tgp_blist_peer_get_purple_name (TLS, TGL_MK_USER (M->action.user));
+          
           txt = g_strdup_printf (_("%1$s deleted user %2$s."), txt_user, alias);
           
-          purple_conv_chat_remove_user (purple_conversation_get_chat_data (conv),
-                                        tgp_blist_peer_get_purple_name (TLS, TGL_MK_USER (M->action.user)), txt);
+          g_return_val_if_fail (aliasLeft, txt);
+          
+          purple_conv_chat_remove_user (purple_conversation_get_chat_data (conv), aliasLeft, txt);
           if (M->action.user == tgl_get_peer_id (TLS->our_id)) {
             purple_conv_chat_left (purple_conversation_get_chat_data (conv));
           }
@@ -243,6 +246,9 @@ void tgp_msg_sys_out (struct tgl_state *TLS, const char *msg, tgl_peer_id_t to_i
     case TGL_PEER_ENCR_CHAT: {
       const char *name = tgp_blist_peer_get_purple_name (TLS, to_id);
       PurpleConversation *conv = p2tgl_find_conversation_with_account (TLS, to_id);
+      
+      g_return_if_fail (name);
+
       if (! conv) {
         conv = purple_conversation_new (PURPLE_CONV_TYPE_IM, tg_get_acc (TLS), name);
       }
@@ -357,6 +363,9 @@ static char *tgp_msg_sticker_display (struct tgl_state *TLS, tgl_peer_id_t from,
   *flags |= PURPLE_MESSAGE_IMAGES;
 #else
   const char *txt_user = tgp_blist_peer_get_purple_name (TLS, from);
+  
+  g_return_val_if_fail (txt_user, NULL);
+  
   text = g_strdup_printf (_("%s sent a sticker."), txt_user);
   *flags |= PURPLE_MESSAGE_SYSTEM;
 #endif