diff --git a/net/inet/inet_close.c b/net/inet/inet_close.c
index 31c20346d1..c9f9648dac 100644
--- a/net/inet/inet_close.c
+++ b/net/inet/inet_close.c
@@ -1,7 +1,7 @@
 /****************************************************************************
  * net/inet/inet_close.c
  *
- *   Copyright (C) 2007-2017 Gregory Nutt. All rights reserved.
+ *   Copyright (C) 2007-2017, 2019 Gregory Nutt. All rights reserved.
  *   Author: Gregory Nutt <gnutt@nuttx.org>
  *
  * Redistribution and use in source and binary forms, with or without
@@ -127,10 +127,13 @@ static uint16_t tcp_close_eventhandler(FAR struct net_driver_s *dev,
 
       if (pstate != NULL)
         {
-          /* Wake up the waiting thread with a successful result */
+          if (conn->tcpstateflags == TCP_CLOSED)
+            {
+              /* Wake up the waiting thread with a successful result */
 
-          pstate->cl_result = OK;
-          goto end_wait;
+              pstate->cl_result = OK;
+              goto end_wait;
+            }
         }
 
       /* Otherwise, nothing is waiting on the close event and we can perform
@@ -566,7 +569,8 @@ int inet_close(FAR struct socket *psock)
               tcp_close_monitor(psock);
             }
 #else
-        nwarn("WARNING: SOCK_STREAM support is not available in this configuration\n");
+        nwarn("WARNING: SOCK_STREAM support is not available in this "
+              "configuration\n");
         return -EAFNOSUPPORT;
 #endif /* NET_TCP_HAVE_STACK */
         }
@@ -606,7 +610,8 @@ int inet_close(FAR struct socket *psock)
               conn->crefs--;
             }
 #else
-          nwarn("WARNING: SOCK_DGRAM support is not available in this configuration\n");
+          nwarn("WARNING: SOCK_DGRAM support is not available in this "
+                "configuration\n");
           return -EAFNOSUPPORT;
 #endif /* NET_UDP_HAVE_STACK */
         }
diff --git a/net/tcp/tcp_appsend.c b/net/tcp/tcp_appsend.c
index edff17d107..7cfd57df53 100644
--- a/net/tcp/tcp_appsend.c
+++ b/net/tcp/tcp_appsend.c
@@ -143,11 +143,14 @@ void tcp_appsend(FAR struct net_driver_s *dev, FAR struct tcp_conn_s *conn,
   else if ((result & TCP_CLOSE) != 0)
     {
       conn->tcpstateflags = TCP_FIN_WAIT_1;
-      conn->unacked  = 1;
-      conn->nrtx     = 0;
+      conn->unacked       = 1;
+      conn->nrtx          = 0;
+#ifdef CONFIG_NET_TCP_WRITE_BUFFERS
+      conn->sndseq_max    = tcp_getsequence(conn->sndseq) + 1;
+#endif
       ninfo("TCP state: TCP_FIN_WAIT_1\n");
 
-      dev->d_sndlen  = 0;
+      dev->d_sndlen       = 0;
       tcp_send(dev, conn, TCP_FIN | TCP_ACK, hdrlen);
     }
 
diff --git a/net/tcp/tcp_input.c b/net/tcp/tcp_input.c
index 08fc96155a..a30ba4dab5 100644
--- a/net/tcp/tcp_input.c
+++ b/net/tcp/tcp_input.c
@@ -524,7 +524,7 @@ found:
        */
 
       ninfo("sndseq: %08x->%08x unackseq: %08x new unacked: %d\n",
-            conn->sndseq, ackseq, unackseq, conn->unacked);
+            tcp_getsequence(conn->sndseq), ackseq, unackseq, conn->unacked);
       tcp_setsequence(conn->sndseq, ackseq);
 
       /* Do RTT estimation, unless we have done retransmissions. */
@@ -785,6 +785,9 @@ found:
             conn->tcpstateflags = TCP_LAST_ACK;
             conn->unacked       = 1;
             conn->nrtx          = 0;
+#ifdef CONFIG_NET_TCP_WRITE_BUFFERS
+            conn->sndseq_max    = tcp_getsequence(conn->sndseq) + 1;
+#endif
             ninfo("TCP state: TCP_LAST_ACK\n");
 
             tcp_send(dev, conn, TCP_FIN | TCP_ACK, tcpiplen);
@@ -932,11 +935,10 @@ found:
 
         if ((tcp->flags & TCP_FIN) != 0)
           {
-            if ((flags & TCP_ACKDATA) != 0)
+            if ((flags & TCP_ACKDATA) != 0 && conn->unacked == 0)
               {
                 conn->tcpstateflags = TCP_TIME_WAIT;
                 conn->timer         = 0;
-                conn->unacked       = 0;
                 ninfo("TCP state: TCP_TIME_WAIT\n");
               }
             else
@@ -950,10 +952,9 @@ found:
             tcp_send(dev, conn, TCP_ACK, tcpiplen);
             return;
           }
-        else if ((flags & TCP_ACKDATA) != 0)
+        else if ((flags & TCP_ACKDATA) != 0 && conn->unacked == 0)
           {
             conn->tcpstateflags = TCP_FIN_WAIT_2;
-            conn->unacked = 0;
             ninfo("TCP state: TCP_FIN_WAIT_2\n");
             goto drop;
           }
diff --git a/sched/environ/env_getenv.c b/sched/environ/env_getenv.c
index 260d31655c..029c42e4ba 100644
--- a/sched/environ/env_getenv.c
+++ b/sched/environ/env_getenv.c
@@ -81,7 +81,7 @@ FAR char *getenv(FAR const char *name)
 
   /* Verify that a string was passed */
 
-  if (!name)
+  if (name == NULL)
     {
       ret = EINVAL;
       goto errout;
@@ -95,7 +95,7 @@ FAR char *getenv(FAR const char *name)
 
   /* Check if the variable exists */
 
-  if (!group || (pvar = env_findvar(group, name)) == NULL)
+  if (group == NULL || (pvar = env_findvar(group, name)) == NULL)
     {
       ret = ENOENT;
       goto errout_with_lock;
@@ -104,7 +104,7 @@ FAR char *getenv(FAR const char *name)
   /* It does!  Get the value sub-string from the name=value string */
 
   pvalue = strchr(pvar, '=');
-  if (!pvalue)
+  if (pvalue == NULL)
     {
       /* The name=value string has no '='  This is a bug! */