diff --git a/test/unit/tcp/tcp_helper.c b/test/unit/tcp/tcp_helper.c
index ad0f657d..4a28b869 100644
--- a/test/unit/tcp/tcp_helper.c
+++ b/test/unit/tcp/tcp_helper.c
@@ -33,6 +33,8 @@ tcp_remove_all(void)
   tcp_remove(tcp_tw_pcbs);
   fail_unless(lwip_stats.memp[MEMP_TCP_PCB].used == 0);
   fail_unless(lwip_stats.memp[MEMP_TCP_PCB_LISTEN].used == 0);
+  fail_unless(lwip_stats.memp[MEMP_TCP_SEG].used == 0);
+  fail_unless(lwip_stats.memp[MEMP_PBUF_POOL].used == 0);
 }
 
 /** Create a TCP segment usable for passing to tcp_input
@@ -56,8 +58,9 @@ tcp_create_segment(struct ip_addr* src_ip, struct ip_addr* dst_ip,
   struct pbuf* p;
   struct ip_hdr* iphdr;
   struct tcp_hdr* tcphdr;
+  u16_t pbuf_len = sizeof(struct ip_hdr) + sizeof(struct tcp_hdr) + data_len;
 
-  p = pbuf_alloc(PBUF_RAW, sizeof(struct ip_hdr) + sizeof(struct tcp_hdr) + data_len, PBUF_RAM);
+  p = pbuf_alloc(PBUF_RAW, pbuf_len, PBUF_POOL);
   EXPECT_RETNULL(p != NULL);
   EXPECT_RETNULL(p->next == NULL);
 
diff --git a/test/unit/tcp/test_tcp_oos.c b/test/unit/tcp/test_tcp_oos.c
index e3fe9fa8..0cef04ef 100644
--- a/test/unit/tcp/test_tcp_oos.c
+++ b/test/unit/tcp/test_tcp_oos.c
@@ -31,8 +31,9 @@ tcp_oos_teardown(void)
 /* Test functions */
 
 /** create multiple segments and pass them to tcp_input in a wrong
- * order to see if ooseq-caching works correctly */
-START_TEST(test_tcp_recv_ooseq)
+ * order to see if ooseq-caching works correctly
+ * FIN is received in out-of-sequence segments only */
+START_TEST(test_tcp_recv_ooseq_FIN_OOSEQ)
 {
   struct test_tcp_counters counters;
   struct tcp_pcb* pcb;
@@ -82,7 +83,8 @@ START_TEST(test_tcp_recv_ooseq)
   EXPECT(p1 != NULL);
   EXPECT(p2 != NULL);
   EXPECT(p3 != NULL);
-  if ((pinseq != NULL) && (p1 != NULL) && (p2 != NULL) && (p3 != NULL)) {
+  EXPECT(p4 != NULL);
+  if ((pinseq != NULL) && (p1 != NULL) && (p2 != NULL) && (p3 != NULL) && (p4 != NULL)) {
     /* pass the segment to tcp_input */
     tcp_input(p1, &netif);
     /* check if counters are as expected */
@@ -137,12 +139,169 @@ START_TEST(test_tcp_recv_ooseq)
 END_TEST
 
 
+/** create multiple segments and pass them to tcp_input in a wrong
+ * order to see if ooseq-caching works correctly
+ * FIN is received IN-SEQUENCE at the end */
+START_TEST(test_tcp_recv_ooseq_FIN_INSEQ)
+{
+  struct test_tcp_counters counters;
+  struct tcp_pcb* pcb;
+  struct pbuf *p1, *p2, *p3, *p4, *p5, *p6, *pinseq, *pinseqFIN;
+  char data[] = {
+     1,  2,  3,  4,
+     5,  6,  7,  8,
+     9, 10, 11, 12,
+    13, 14, 15, 16};
+  struct ip_addr remote_ip, local_ip;
+  u16_t data_len;
+  u16_t remote_port = 0x100, local_port = 0x101;
+  struct netif netif;
+  LWIP_UNUSED_ARG(_i);
+
+  /* initialize local vars */
+  memset(&netif, 0, sizeof(netif));
+  IP4_ADDR(&local_ip, 192, 168, 1, 1);
+  IP4_ADDR(&remote_ip, 192, 168, 1, 2);
+  data_len = sizeof(data);
+  /* initialize counter struct */
+  memset(&counters, 0, sizeof(counters));
+  counters.expected_data_len = data_len;
+  counters.expected_data = data;
+
+  /* create and initialize the pcb */
+  pcb = test_tcp_new_counters_pcb(&counters);
+  EXPECT_RET(pcb != NULL);
+  tcp_set_state(pcb, ESTABLISHED, &local_ip, &remote_ip, local_port, remote_port);
+
+  /* create segments */
+  /* p1: 7 bytes - 2 before FIN */
+  /*     seqno: 1..2 */
+  p1     = tcp_create_rx_segment(pcb, &data[1],  2, 1, 0, TCP_ACK);
+  /* p2: 4 bytes before p1, including the first 4 bytes of p1 (partly duplicate) */
+  /*     seqno: 4..11 */
+  p2     = tcp_create_rx_segment(pcb, &data[4],  8, 4, 0, TCP_ACK);
+  /* p3: same as p2 but 2 bytes longer and one byte more at the front */
+  /*     seqno: 3..13 */
+  p3     = tcp_create_rx_segment(pcb, &data[3], 11, 3, 0, TCP_ACK);
+  /* p4: 13 bytes - 2 before FIN - should be ignored as contained in p1 and p3 */
+  /*     seqno: 2..13 */
+  p4     = tcp_create_rx_segment(pcb, &data[2], 12, 2, 0, TCP_ACK);
+  /* pinseq is the first segment that is held back to create ooseq! */
+  /*     seqno: 0..3 */
+  pinseq = tcp_create_rx_segment(pcb, &data[0],  4, 0, 0, TCP_ACK);
+  /* p5: last byte before FIN */
+  /*     seqno: 15 */
+  p5     = tcp_create_rx_segment(pcb, &data[15], 1, 15, 0, TCP_ACK);
+  /* p6: same as p5, should be ignored */
+  p6     = tcp_create_rx_segment(pcb, &data[15], 1, 15, 0, TCP_ACK);
+  /* pinseqFIN: last 2 bytes plus FIN */
+  /*     only segment containing seqno 14 and FIN */
+  pinseqFIN = tcp_create_rx_segment(pcb,  &data[14], 2, 14, 0, TCP_ACK|TCP_FIN);
+  EXPECT(pinseq != NULL);
+  EXPECT(p1 != NULL);
+  EXPECT(p2 != NULL);
+  EXPECT(p3 != NULL);
+  EXPECT(p4 != NULL);
+  EXPECT(p5 != NULL);
+  EXPECT(p6 != NULL);
+  EXPECT(pinseqFIN != NULL);
+  if ((pinseq != NULL) && (p1 != NULL) && (p2 != NULL) && (p3 != NULL) && (p4 != NULL)
+    && (p5 != NULL) && (p6 != NULL) && (pinseqFIN != NULL)) {
+    /* pass the segment to tcp_input */
+    tcp_input(p1, &netif);
+    /* check if counters are as expected */
+    EXPECT(counters.close_calls == 0);
+    EXPECT(counters.recv_calls == 0);
+    EXPECT(counters.recved_bytes == 0);
+    EXPECT(counters.err_calls == 0);
+    /* @todo check ooseq queue? */
+
+    /* pass the segment to tcp_input */
+    tcp_input(p2, &netif);
+    /* check if counters are as expected */
+    EXPECT(counters.close_calls == 0);
+    EXPECT(counters.recv_calls == 0);
+    EXPECT(counters.recved_bytes == 0);
+    EXPECT(counters.err_calls == 0);
+    /* @todo check ooseq queue? */
+
+    /* pass the segment to tcp_input */
+    tcp_input(p3, &netif);
+    /* check if counters are as expected */
+    EXPECT(counters.close_calls == 0);
+    EXPECT(counters.recv_calls == 0);
+    EXPECT(counters.recved_bytes == 0);
+    EXPECT(counters.err_calls == 0);
+    /* @todo check ooseq queue? */
+
+    /* pass the segment to tcp_input */
+    tcp_input(p4, &netif);
+    /* check if counters are as expected */
+    EXPECT(counters.close_calls == 0);
+    EXPECT(counters.recv_calls == 0);
+    EXPECT(counters.recved_bytes == 0);
+    EXPECT(counters.err_calls == 0);
+    /* @todo check ooseq queue? */
+
+    /* pass the segment to tcp_input */
+    tcp_input(pinseq, &netif);
+    /* check if counters are as expected */
+    EXPECT(counters.close_calls == 0);
+    EXPECT(counters.recv_calls == 1);
+    EXPECT(counters.recved_bytes == 14);
+    EXPECT(counters.err_calls == 0);
+    EXPECT(pcb->ooseq == NULL);
+
+    /* pass the segment to tcp_input */
+    tcp_input(p5, &netif);
+    /* check if counters are as expected */
+    EXPECT(counters.close_calls == 0);
+    EXPECT(counters.recv_calls == 1);
+    EXPECT(counters.recved_bytes == 14);
+    EXPECT(counters.err_calls == 0);
+    /* @todo check ooseq queue? */
+    EXPECT(pcb->ooseq != NULL);
+    if(pcb->ooseq != NULL) {
+      EXPECT(pcb->ooseq->next == NULL);
+    }
+
+    /* pass the segment to tcp_input */
+    tcp_input(p6, &netif);
+    /* check if counters are as expected */
+    EXPECT(counters.close_calls == 0);
+    EXPECT(counters.recv_calls == 1);
+    EXPECT(counters.recved_bytes == 14);
+    EXPECT(counters.err_calls == 0);
+    /* @todo check ooseq queue? */
+    EXPECT(pcb->ooseq != NULL);
+    if(pcb->ooseq != NULL) {
+      EXPECT(pcb->ooseq->next == NULL);
+    }
+
+    /* pass the segment to tcp_input */
+    tcp_input(pinseqFIN, &netif);
+    /* check if counters are as expected */
+    EXPECT(counters.close_calls == 1);
+    EXPECT(counters.recv_calls == 2);
+    EXPECT(counters.recved_bytes == data_len);
+    EXPECT(counters.err_calls == 0);
+    EXPECT(pcb->ooseq == NULL);
+  }
+
+  /* make sure the pcb is freed */
+  EXPECT(lwip_stats.memp[MEMP_TCP_PCB].used == 1);
+  tcp_abort(pcb);
+  EXPECT(lwip_stats.memp[MEMP_TCP_PCB].used == 0);
+}
+END_TEST
+
 /** Create the suite including all tests for this module */
 Suite *
 tcp_oos_suite(void)
 {
   TFun tests[] = {
-    test_tcp_recv_ooseq,
+    test_tcp_recv_ooseq_FIN_OOSEQ,
+    test_tcp_recv_ooseq_FIN_INSEQ,
   };
   return create_suite("TCP_OOS", tests, sizeof(tests)/sizeof(TFun), tcp_oos_setup, tcp_oos_teardown);
 }