diff --git a/CHANGELOG b/CHANGELOG
index d6bd1552..ff08396d 100644
--- a/CHANGELOG
+++ b/CHANGELOG
@@ -46,6 +46,9 @@ HISTORY
 
   ++ Bugfixes:
 
+  2009-10-27: Kieran Mansley
+  * tcp_in.c: fix BUG#27445: grow cwnd with every duplicate ACK
+
   2009-10-25: Simon Goldschmidt
   * tcp.h: bug-fix in the TCP_EVENT_RECV macro (has to call tcp_recved if
     pcb->recv is NULL to keep rcv_wnd correct)
diff --git a/src/core/tcp_in.c b/src/core/tcp_in.c
index dc6d72ca..2efd3196 100644
--- a/src/core/tcp_in.c
+++ b/src/core/tcp_in.c
@@ -793,44 +793,44 @@ tcp_receive(struct tcp_pcb *pcb)
       pcb->acked = 0;
 
       if (pcb->snd_wl2 + pcb->snd_wnd == right_wnd_edge){
-        if (pcb->unacked != NULL) {
-          ++pcb->dupacks;
-          if (pcb->dupacks >= 3) {
-            if (!(pcb->flags & TF_INFR)) {
-              /* This is fast retransmit. Retransmit the first unacked segment. */
-              LWIP_DEBUGF(TCP_FR_DEBUG, ("tcp_receive: dupacks %"U16_F" (%"U32_F"), fast retransmit %"U32_F"\n",
-                                         (u16_t)pcb->dupacks, pcb->lastack,
-                                         ntohl(pcb->unacked->tcphdr->seqno)));
-              tcp_rexmit(pcb);
-              /* Set ssthresh to max (FlightSize / 2, 2*SMSS) */
-              /*pcb->ssthresh = LWIP_MAX((pcb->snd_max -
-                                        pcb->lastack) / 2,
-                                        2 * pcb->mss);*/
-              /* Set ssthresh to half of the minimum of the current cwnd and the advertised window */
-              if (pcb->cwnd > pcb->snd_wnd)
-                pcb->ssthresh = pcb->snd_wnd / 2;
-              else
-                pcb->ssthresh = pcb->cwnd / 2;
+        ++pcb->dupacks;
 
-              /* The minimum value for ssthresh should be 2 MSS */
-              if (pcb->ssthresh < 2*pcb->mss) {
-                LWIP_DEBUGF(TCP_FR_DEBUG, ("tcp_receive: The minimum value for ssthresh %"U16_F" should be min 2 mss %"U16_F"...\n", pcb->ssthresh, 2*pcb->mss));
-                pcb->ssthresh = 2*pcb->mss;
-              }
-
-              pcb->cwnd = pcb->ssthresh + 3 * pcb->mss;
-              pcb->flags |= TF_INFR;
-            } else {
-              /* Inflate the congestion window, but not if it means that
-                 the value overflows. */
-              if ((u16_t)(pcb->cwnd + pcb->mss) > pcb->cwnd) {
-                pcb->cwnd += pcb->mss;
-              }
+        if (pcb->dupacks >= 3) {
+          if (!(pcb->flags & TF_INFR) && pcb->unacked != NULL) {
+            /* This is fast retransmit. Retransmit the first unacked segment. */
+            LWIP_DEBUGF(TCP_FR_DEBUG, ("tcp_receive: dupacks %"U16_F" (%"U32_F"), fast retransmit %"U32_F"\n",
+                                       (u16_t)pcb->dupacks, pcb->lastack,
+                                       ntohl(pcb->unacked->tcphdr->seqno)));
+            tcp_rexmit(pcb);
+            /* Set ssthresh to max (FlightSize / 2, 2*SMSS) */
+            /*pcb->ssthresh = LWIP_MAX((pcb->snd_max -
+              pcb->lastack) / 2,
+              2 * pcb->mss);*/
+            /* Set ssthresh to half of the minimum of the current cwnd and the advertised window */
+            if (pcb->cwnd > pcb->snd_wnd)
+              pcb->ssthresh = pcb->snd_wnd / 2;
+            else
+              pcb->ssthresh = pcb->cwnd / 2;
+            
+            /* The minimum value for ssthresh should be 2 MSS */
+            if (pcb->ssthresh < 2*pcb->mss) {
+              LWIP_DEBUGF(TCP_FR_DEBUG, ("tcp_receive: The minimum value for ssthresh %"U16_F" should be min 2 mss %"U16_F"...\n", pcb->ssthresh, 2*pcb->mss));
+              pcb->ssthresh = 2*pcb->mss;
+            }
+            
+            pcb->cwnd = pcb->ssthresh + 3 * pcb->mss;
+            pcb->flags |= TF_INFR;
+          } else {
+            /* Inflate the congestion window, but not if it means that
+               the value overflows. */
+            if ((u16_t)(pcb->cwnd + pcb->mss) > pcb->cwnd) {
+              pcb->cwnd += pcb->mss;
             }
           }
-        } else {
-          pcb->dupacks = 0;
         }
+
+        if (pcb->unacked == NULL && pcb->unsent == NULL)
+          pcb->dupacks = 0;
       } else {
         LWIP_DEBUGF(TCP_FR_DEBUG, ("tcp_receive: dupack averted %"U32_F" %"U32_F"\n",
                                    pcb->snd_wl2 + pcb->snd_wnd, right_wnd_edge));