Index: uspace/srv/net/tcp/ncsim.c
===================================================================
--- uspace/srv/net/tcp/ncsim.c	(revision d21e935c48590982d3b2557f2fe140922a9a4ba4)
+++ uspace/srv/net/tcp/ncsim.c	(revision 88a68199cabf487ae2586a1a871f7b1c34da4804)
@@ -44,5 +44,5 @@
 #include <io/log.h>
 #include <stdlib.h>
-#include <thread.h>
+#include <fibril.h>
 #include "conn.h"
 #include "ncsim.h"
@@ -119,6 +119,6 @@
 }
 
-/** Network condition simulator handler thread. */
-static void tcp_ncsim_thread(void *arg)
+/** Network condition simulator handler fibril. */
+static int tcp_ncsim_fibril(void *arg)
 {
 	link_t *link;
@@ -126,5 +126,5 @@
 	int rc;
 
-	log_msg(LVL_DEBUG, "tcp_ncsim_thread()");
+	log_msg(LVL_DEBUG, "tcp_ncsim_fibril()");
 
 
@@ -151,19 +151,23 @@
 		free(sqe);
 	}
+
+	/* Not reached */
+	return 0;
 }
 
-/** Start simulator handler thread. */
-void tcp_ncsim_thread_start(void)
+/** Start simulator handler fibril. */
+void tcp_ncsim_fibril_start(void)
 {
-	thread_id_t tid;
-        int rc;
+	fid_t fid;
 
-	log_msg(LVL_DEBUG, "tcp_ncsim_thread_start()");
+	log_msg(LVL_DEBUG, "tcp_ncsim_fibril_start()");
 
-	rc = thread_create(tcp_ncsim_thread, NULL, "ncsim", &tid);
-	if (rc != EOK) {
-		log_msg(LVL_ERROR, "Failed creating ncsim thread.");
+	fid = fibril_create(tcp_ncsim_fibril, NULL);
+	if (fid == 0) {
+		log_msg(LVL_ERROR, "Failed creating ncsim fibril.");
 		return;
 	}
+
+	fibril_add_ready(fid);
 }
 
Index: uspace/srv/net/tcp/ncsim.h
===================================================================
--- uspace/srv/net/tcp/ncsim.h	(revision d21e935c48590982d3b2557f2fe140922a9a4ba4)
+++ uspace/srv/net/tcp/ncsim.h	(revision 88a68199cabf487ae2586a1a871f7b1c34da4804)
@@ -40,6 +40,5 @@
 extern void tcp_ncsim_init(void);
 extern void tcp_ncsim_bounce_seg(tcp_sockpair_t *, tcp_segment_t *);
-extern void tcp_ncsim_thread_start(void);
-
+extern void tcp_ncsim_fibril_start(void);
 
 #endif
Index: uspace/srv/net/tcp/rqueue.c
===================================================================
--- uspace/srv/net/tcp/rqueue.c	(revision d21e935c48590982d3b2557f2fe140922a9a4ba4)
+++ uspace/srv/net/tcp/rqueue.c	(revision 88a68199cabf487ae2586a1a871f7b1c34da4804)
@@ -39,5 +39,5 @@
 #include <io/log.h>
 #include <stdlib.h>
-#include <thread.h>
+#include <fibril.h>
 #include "conn.h"
 #include "pdu.h"
@@ -128,11 +128,11 @@
 }
 
-/** Receive queue handler thread. */
-static void tcp_rqueue_thread(void *arg)
+/** Receive queue handler fibril. */
+static int tcp_rqueue_fibril(void *arg)
 {
 	link_t *link;
 	tcp_rqueue_entry_t *rqe;
 
-	log_msg(LVL_DEBUG, "tcp_rqueue_thread()");
+	log_msg(LVL_DEBUG, "tcp_rqueue_fibril()");
 
 	while (true) {
@@ -142,19 +142,23 @@
 		tcp_as_segment_arrived(&rqe->sp, rqe->seg);
 	}
+
+	/* Not reached */
+	return 0;
 }
 
-/** Start receive queue handler thread. */
-void tcp_rqueue_thread_start(void)
+/** Start receive queue handler fibril. */
+void tcp_rqueue_fibril_start(void)
 {
-	thread_id_t tid;
-        int rc;
+	fid_t fid;
 
-	log_msg(LVL_DEBUG, "tcp_rqueue_thread_start()");
+	log_msg(LVL_DEBUG, "tcp_rqueue_fibril_start()");
 
-	rc = thread_create(tcp_rqueue_thread, NULL, "rqueue", &tid);
-	if (rc != EOK) {
-		log_msg(LVL_ERROR, "Failed creating rqueue thread.");
+	fid = fibril_create(tcp_rqueue_fibril, NULL);
+	if (fid == 0) {
+		log_msg(LVL_ERROR, "Failed creating rqueue fibril.");
 		return;
 	}
+
+	fibril_add_ready(fid);
 }
 
Index: uspace/srv/net/tcp/rqueue.h
===================================================================
--- uspace/srv/net/tcp/rqueue.h	(revision d21e935c48590982d3b2557f2fe140922a9a4ba4)
+++ uspace/srv/net/tcp/rqueue.h	(revision 88a68199cabf487ae2586a1a871f7b1c34da4804)
@@ -42,5 +42,5 @@
 extern void tcp_rqueue_insert_seg(tcp_sockpair_t *, tcp_segment_t *);
 extern void tcp_rqueue_handler(void *);
-extern void tcp_rqueue_thread_start(void);
+extern void tcp_rqueue_fibril_start(void);
 
 
Index: uspace/srv/net/tcp/tcp.c
===================================================================
--- uspace/srv/net/tcp/tcp.c	(revision d21e935c48590982d3b2557f2fe140922a9a4ba4)
+++ uspace/srv/net/tcp/tcp.c	(revision 88a68199cabf487ae2586a1a871f7b1c34da4804)
@@ -180,8 +180,8 @@
 
 	tcp_rqueue_init();
-	tcp_rqueue_thread_start();
+	tcp_rqueue_fibril_start();
 
 	tcp_ncsim_init();
-	tcp_ncsim_thread_start();
+	tcp_ncsim_fibril_start();
 
 	if (0) tcp_test();
Index: uspace/srv/net/tcp/test.c
===================================================================
--- uspace/srv/net/tcp/test.c	(revision d21e935c48590982d3b2557f2fe140922a9a4ba4)
+++ uspace/srv/net/tcp/test.c	(revision 88a68199cabf487ae2586a1a871f7b1c34da4804)
@@ -38,5 +38,5 @@
 #include <errno.h>
 #include <stdio.h>
-#include <thread.h>
+#include <fibril.h>
 #include <str.h>
 #include "tcp_type.h"
@@ -47,5 +47,5 @@
 #define RCV_BUF_SIZE 64
 
-static void test_srv(void *arg)
+static int test_srv(void *arg)
 {
 	tcp_conn_t *conn;
@@ -84,7 +84,8 @@
 
 	printf("test_srv() terminating\n");
+	return 0;
 }
 
-static void test_cli(void *arg)
+static int test_cli(void *arg)
 {
 	tcp_conn_t *conn;
@@ -112,11 +113,12 @@
 	printf("C: User close...\n");
 	tcp_uc_close(conn);
+
+	return 0;
 }
 
 void tcp_test(void)
 {
-	thread_id_t srv_tid;
-	thread_id_t cli_tid;
-	int rc;
+	fid_t srv_fid;
+	fid_t cli_fid;
 
 	printf("tcp_test()\n");
@@ -125,17 +127,21 @@
 
 	if (0) {
-		rc = thread_create(test_srv, NULL, "test_srv", &srv_tid);
-		if (rc != EOK) {
-			printf("Failed to create server thread.\n");
+		srv_fid = fibril_create(test_srv, NULL);
+		if (srv_fid == 0) {
+			printf("Failed to create server fibril.\n");
 			return;
 		}
+
+		fibril_add_ready(srv_fid);
 	}
 
 	if (0) {
-		rc = thread_create(test_cli, NULL, "test_cli", &cli_tid);
-		if (rc != EOK) {
-			printf("Failed to create client thread.\n");
+		cli_fid = fibril_create(test_cli, NULL);
+		if (cli_fid == 0) {
+			printf("Failed to create client fibril.\n");
 			return;
 		}
+
+		fibril_add_ready(cli_fid);
 	}
 }