diff --git a/libtransmission/port-forwarding.c b/libtransmission/port-forwarding.c
index a031f3c4e..18b3a6621 100644
--- a/libtransmission/port-forwarding.c
+++ b/libtransmission/port-forwarding.c
@@ -44,6 +44,7 @@ struct tr_shared
     tr_port               publicPort;
 
     tr_timer            * pulseTimer;
+    tr_timer            * recheckTimer;
 
     tr_upnp             * upnp;
     tr_natpmp           * natpmp;
@@ -83,7 +84,7 @@ getNatStateStr( int state )
 }
 
 static void
-natPulse( tr_shared * s )
+natPulse( tr_shared * s, tr_bool doPortCheck )
 {
     const tr_port port = s->publicPort;
     const int     isEnabled = s->isEnabled && !s->isShuttingDown;
@@ -92,7 +93,7 @@ natPulse( tr_shared * s )
 
     oldStatus = tr_sharedTraversalStatus( s );
     s->natpmpStatus = tr_natpmpPulse( s->natpmp, port, isEnabled );
-    s->upnpStatus = tr_upnpPulse( s->upnp, port, isEnabled );
+    s->upnpStatus = tr_upnpPulse( s->upnp, port, isEnabled, doPortCheck );
     newStatus = tr_sharedTraversalStatus( s );
 
     if( newStatus != oldStatus )
@@ -186,10 +187,10 @@ incomingPeersPulse( tr_shared * s )
 static int
 sharedPulse( void * vshared )
 {
-    tr_bool keepPulsing = 1;
+    tr_bool keepPulsing = TRUE;
     tr_shared * shared = vshared;
 
-    natPulse( shared );
+    natPulse( shared, FALSE );
 
     if( !shared->isShuttingDown )
     {
@@ -199,18 +200,34 @@ sharedPulse( void * vshared )
     {
         tr_ninf( getKey( ), _( "Stopped" ) );
         tr_timerFree( &shared->pulseTimer );
+        tr_timerFree( &shared->recheckTimer );
         tr_socketListForEach( shared->bindSockets, &closeCb, shared );
         tr_socketListFree( shared->bindSockets );
         tr_natpmpClose( shared->natpmp );
         tr_upnpClose( shared->upnp );
         shared->session->shared = NULL;
         tr_free( shared );
-        keepPulsing = 0;
+        keepPulsing = FALSE;
     }
 
     return keepPulsing;
 }
 
+static int
+recheckPulse( void * vshared )
+{
+    tr_bool keepPulsing = TRUE;
+    tr_shared * shared = vshared;
+
+    tr_ninf( getKey( ), _( "Checking to see if port %d is still open" ), shared->publicPort );
+    natPulse( shared, TRUE );
+
+    if( shared->isShuttingDown )
+        keepPulsing = FALSE;
+
+    return keepPulsing;
+}
+
 /***
 ****
 ***/
@@ -225,12 +242,12 @@ tr_sharedInit( tr_session  * session,
 
     s->session      = session;
     s->publicPort   = publicPort;
-    s->shouldChange = TRUE;
     s->bindSockets  = socks;
     s->shouldChange = TRUE;
     s->natpmp       = tr_natpmpInit( );
     s->upnp         = tr_upnpInit( );
     s->pulseTimer   = tr_timerNew( session, sharedPulse, s, 1000 );
+    s->recheckTimer = tr_timerNew( session, recheckPulse, s, 1000*60*20 ); /* 20 minutes */
     s->isEnabled    = isEnabled;
     s->upnpStatus   = TR_PORT_UNMAPPED;
     s->natpmpStatus = TR_PORT_UNMAPPED;
diff --git a/libtransmission/upnp.c b/libtransmission/upnp.c
index dbf950e19..72ce3d02c 100644
--- a/libtransmission/upnp.c
+++ b/libtransmission/upnp.c
@@ -80,7 +80,8 @@ tr_upnpClose( tr_upnp * handle )
 int
 tr_upnpPulse( tr_upnp * handle,
               int       port,
-              int       isEnabled )
+              int       isEnabled,
+              int       doPortCheck )
 {
     int ret;
 
@@ -127,6 +128,24 @@ tr_upnpPulse( tr_upnp * handle,
             handle->state = TR_UPNP_UNMAP;
     }
 
+    if( isEnabled && handle->isMapped && doPortCheck )
+    {
+        char portStr[8];
+        char intPort[8];
+        char intClient[16];
+        int i;
+
+        tr_snprintf( portStr, sizeof( portStr ), "%d", handle->port );
+        i = UPNP_GetSpecificPortMappingEntry( handle->urls.controlURL,
+                                              handle->data.servicetype, portStr,
+                                              "TCP", intClient, intPort );
+        if( i != UPNPCOMMAND_SUCCESS )
+        {
+            tr_ninf( getKey( ), _( "Port %d isn't forwarded" ), handle->port );
+            handle->isMapped = FALSE;
+        }
+    }
+
     if( handle->state == TR_UPNP_UNMAP )
     {
         char portStr[16];
diff --git a/libtransmission/upnp.h b/libtransmission/upnp.h
index a6e2ce4ca..c5d220d05 100644
--- a/libtransmission/upnp.h
+++ b/libtransmission/upnp.h
@@ -25,6 +25,6 @@ void      tr_upnpClose( tr_upnp * );
 
 int       tr_upnpPulse(         tr_upnp *,
                             int port,
-                            int isEnabled );
-
+                            int isEnabled,
+                            int doPortCheck );
 #endif