diff --git a/src/client.c b/src/client.c
index 76f9d69..bccf8ca 100644
--- a/src/client.c
+++ b/src/client.c
@@ -289,10 +289,21 @@ static int get_chunk_server(TinyDFS *tdfs, Address *addrs, int num_addrs, ByteQu
         if (!tdfs->chunk_servers[i].used)
            continue;
 
-        if (have_insertection(addrs, num_addrs, tdfs->chunk_servers[i].addrs, tdfs->chunk_servers[i].num_addrs)) {
-            found = i;
-            break;
-        }
+        if (!have_insertection(addrs, num_addrs, tdfs->chunk_servers[i].addrs, tdfs->chunk_servers[i].num_addrs))
+            continue;
+
+        // It's possible that this chunk server's connection
+        // was dropped but we still didn't process the DISCONNECT
+        // event.
+        int conn_idx = tcp_index_from_tag(&tdfs->tcp, found);
+        if (conn_idx < 0)
+            continue;
+
+        if (output)
+            *output = tcp_output_buffer(&tdfs->tcp, conn_idx);
+
+        found = i;
+        break;
     }
 
     if (found == -1) {
@@ -322,14 +333,6 @@ static int get_chunk_server(TinyDFS *tdfs, Address *addrs, int num_addrs, ByteQu
         request_queue_init(&tdfs->chunk_servers[found].reqs);
 
         tdfs->num_chunk_servers++;
-
-    } else {
-
-        int conn_idx = tcp_index_from_tag(&tdfs->tcp, found);
-        assert(conn_idx > -1);
-
-        if (output)
-            *output = tcp_output_buffer(&tdfs->tcp, conn_idx);
     }
 
     return found;
diff --git a/src/metadata_server.c b/src/metadata_server.c
index 4496911..e3c5f32 100644
--- a/src/metadata_server.c
+++ b/src/metadata_server.c
@@ -880,7 +880,7 @@ int metadata_server_step(MetadataServer *state, void **contexts, struct pollfd *
         switch (events[i].type) {
 
             case EVENT_CONNECT:
-            tcp_set_tag(&state->tcp, conn_idx, CONNECTION_TAG_UNKNOWN);
+            tcp_set_tag(&state->tcp, conn_idx, CONNECTION_TAG_UNKNOWN, false);
             break;
 
             case EVENT_DISCONNECT:
@@ -914,9 +914,9 @@ int metadata_server_step(MetadataServer *state, void **contexts, struct pollfd *
                         if (is_chunk_server_message_type(msg_type)) {
                             int chunk_server_idx = state->num_chunk_servers++;
                             chunk_server_peer_init(&state->chunk_servers[chunk_server_idx]);
-                            tcp_set_tag(&state->tcp, conn_idx, chunk_server_idx);
+                            tcp_set_tag(&state->tcp, conn_idx, chunk_server_idx, true);
                         } else {
-                            tcp_set_tag(&state->tcp, conn_idx, CONNECTION_TAG_CLIENT);
+                            tcp_set_tag(&state->tcp, conn_idx, CONNECTION_TAG_CLIENT, false);
                         }
                     }
 
diff --git a/src/tcp.c b/src/tcp.c
index 4752aff..04a9b9c 100644
--- a/src/tcp.c
+++ b/src/tcp.c
@@ -401,8 +401,14 @@ void tcp_close(TCP *tcp, int conn_idx)
     //       if the output buffer is empty, the connection should be closed here.
 }
 
-void tcp_set_tag(TCP *tcp, int conn_idx, int tag)
+void tcp_set_tag(TCP *tcp, int conn_idx, int tag, bool unique)
 {
+    assert(tag != -1);
+
+    if (unique)
+        for (int i = 0; i < tcp->num_conns; i++)
+            assert(tcp->conns[i].tag != tag);
+
     tcp->conns[conn_idx].tag = tag;
 }
 
diff --git a/src/tcp.h b/src/tcp.h
index c27fb2d..015bc7d 100644
--- a/src/tcp.h
+++ b/src/tcp.h
@@ -62,7 +62,7 @@ int  tcp_register_events(TCP *tcp, void **contexts, struct pollfd *polled);
 ByteQueue *tcp_output_buffer(TCP *tcp, int conn_idx);
 int  tcp_connect(TCP *tcp, Address addr, int tag, ByteQueue **output);
 void tcp_close(TCP *tcp, int conn_idx);
-void tcp_set_tag(TCP *tcp, int conn_idx, int tag);
+void tcp_set_tag(TCP *tcp, int conn_idx, int tag, bool unique);
 int  tcp_get_tag(TCP *tcp, int conn_idx);
 
 #endif // TCP_INCLUDED