diff --git a/CMakeLists.txt b/CMakeLists.txt
index c52a42e4a83e06ef2c6d77f488e0105f2c71a147..a290730fe15025eb642efa3867db9212a12f9ec9 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -31,7 +31,6 @@ file(READ version.minor PAHO_VERSION_MINOR)
 file(READ version.patch PAHO_VERSION_PATCH)
 SET(CLIENT_VERSION ${PAHO_VERSION_MAJOR}.${PAHO_VERSION_MINOR}.${PAHO_VERSION_PATCH})
 
-ENABLE_LANGUAGE(CXX)
 INCLUDE(GNUInstallDirs)
 
 STRING(TIMESTAMP BUILD_TIMESTAMP UTC)
diff --git a/src/Clients.h b/src/Clients.h
index 2c6fa8ba1bf4f03694d7ae6e695f2f5eb26955dc..43f1aea9eff98018a02b897367d87b73a4d0dd02 100644
--- a/src/Clients.h
+++ b/src/Clients.h
@@ -1,5 +1,5 @@
 /*******************************************************************************
- * Copyright (c) 2009, 2019 IBM Corp.
+ * Copyright (c) 2009, 2020 IBM Corp.
  *
  * All rights reserved. This program and the accompanying materials
  * are made available under the terms of the Eclipse Public License v2.0
@@ -124,24 +124,24 @@ typedef struct
 	unsigned int good : 1; 			  /**< if we have an error on the socket we turn this off */
 	unsigned int ping_outstanding : 1;
 	signed int connect_state : 4;
-	networkHandles net;
-	int msgID;
-	int keepAliveInterval;
+	networkHandles net;             /**< network info for this client */
+	int msgID;                      /**< the MQTT message id */
+	int keepAliveInterval;          /**< the MQTT keep alive interval */
 	int retryInterval;
-	int maxInflightMessages;
-	willMessages* will;
-	List* inboundMsgs;
-	List* outboundMsgs;				/**< in flight */
-	List* messageQueue;
+	int maxInflightMessages;        /**< the max number of inflight outbound messages we allow */
+	willMessages* will;             /**< the MQTT will message, if any */
+	List* inboundMsgs;              /**< inbound in flight messages */
+	List* outboundMsgs;				/**< outbound in flight messages */
+	List* messageQueue;             /**< inbound complete but undelivered messages */
 	unsigned int qentry_seqno;
-	void* phandle;  /* the persistence handle */
-	MQTTClient_persistence* persistence; /* a persistence implementation */
+	void* phandle;                  /**< the persistence handle */
+	MQTTClient_persistence* persistence; /**< a persistence implementation */
 	void* context; /* calling context - used when calling disconnect_internal */
-	int MQTTVersion;
-	int sessionExpiry; /**< MQTT 5 session expiry */
+	int MQTTVersion;                /**< the version of MQTT being used, 3, 4 or 5 */
+	int sessionExpiry;              /**< MQTT 5 session expiry */
 #if defined(OPENSSL)
-	MQTTClient_SSLOptions *sslopts;
-	SSL_SESSION* session;    /***< SSL session pointer for fast handhake */
+	MQTTClient_SSLOptions *sslopts; /**< the SSL/TLS connect options */
+	SSL_SESSION* session;           /**< SSL session pointer for fast handhake */
 #endif
 } Clients;
 
diff --git a/src/Heap.c b/src/Heap.c
index 7e4588c928241ca2e5af7bf3aeceae99d5e3285d..5caee598971860b54a88f813cf5993dba1c2b223 100644
--- a/src/Heap.c
+++ b/src/Heap.c
@@ -160,13 +160,14 @@ void* mymalloc(char* file, int line, size_t size)
 	storageElement* s = NULL;
 	size_t space = sizeof(storageElement);
 	size_t filenamelen = strlen(file)+1;
+	void* rc = NULL;
 
 	Thread_lock_mutex(heap_mutex);
 	size = Heap_roundup(size);
 	if ((s = malloc(sizeof(storageElement))) == NULL)
 	{
 		Log(LOG_ERROR, 13, errmsg);
-		return NULL;
+		goto exit;
 	}
 	memset(s, 0, sizeof(storageElement));
 
@@ -175,7 +176,7 @@ void* mymalloc(char* file, int line, size_t size)
 	{
 		Log(LOG_ERROR, 13, errmsg);
 		free(s);
-		return NULL;
+		goto exit;
 	}
 	memset(s->file, 0, sizeof(filenamelen));
 
@@ -188,7 +189,7 @@ void* mymalloc(char* file, int line, size_t size)
 		Log(LOG_ERROR, 13, errmsg);
 		free(s->file);
 		free(s);
-		return NULL;
+		goto exit;
 	}
 	memset(s->stack, 0, sizeof(filenamelen));
 	StackTrace_get(Thread_getid(), s->stack, STACK_LEN);
@@ -200,7 +201,7 @@ void* mymalloc(char* file, int line, size_t size)
 		Log(LOG_ERROR, 13, errmsg);
 		free(s->file);
 		free(s);
-		return NULL;
+		goto exit;
 	}
 	memset(s->ptr, 0, size + 2*sizeof(eyecatcherType));
 	space += size + 2*sizeof(eyecatcherType);
@@ -211,8 +212,10 @@ void* mymalloc(char* file, int line, size_t size)
 	state.current_size += size;
 	if (state.current_size > state.max_size)
 		state.max_size = state.current_size;
+	rc = ((eyecatcherType*)(s->ptr)) + 1;	/* skip start eyecatcher */
+exit:
 	Thread_unlock_mutex(heap_mutex);
-	return ((eyecatcherType*)(s->ptr)) + 1;	/* skip start eyecatcher */
+	return rc;
 }
 
 
@@ -336,7 +339,7 @@ void *myrealloc(char* file, int line, void* p, size_t size)
 		if ((s->ptr = realloc(s->ptr, size + 2*sizeof(eyecatcherType))) == NULL)
 		{
 			Log(LOG_ERROR, 13, errmsg);
-			return NULL;
+			goto exit;
 		}
 		space += size + 2*sizeof(eyecatcherType) - s->size;
 		*(eyecatcherType*)(s->ptr) = eyecatcher; /* start eyecatcher */
@@ -350,6 +353,7 @@ void *myrealloc(char* file, int line, void* p, size_t size)
 		rc = s->ptr;
 		TreeAdd(&heap, s, space);
 	}
+exit:
 	Thread_unlock_mutex(heap_mutex);
 	return (rc == NULL) ? NULL : ((eyecatcherType*)(rc)) + 1;	/* skip start eyecatcher */
 }
diff --git a/src/MQTTAsync.c b/src/MQTTAsync.c
index 5fc26ed83ac81a4191aac0378bd8b72c2ae75c7f..a67fbe9710b28dda3049e3829be417363cef1031 100644
--- a/src/MQTTAsync.c
+++ b/src/MQTTAsync.c
@@ -3472,6 +3472,7 @@ static int MQTTAsync_assignMsgId(MQTTAsyncs* m)
 
 	msgid = (msgid == MAX_MSG_ID) ? 1 : msgid + 1;
 	while (ListFindItem(commands, &msgid, cmdMessageIDCompare) ||
+			ListFindItem(m->c->outboundMsgs, &msgid, messageIDCompare) ||
 			ListFindItem(m->responses, &msgid, cmdMessageIDCompare))
 	{
 		msgid = (msgid == MAX_MSG_ID) ? 1 : msgid + 1;
@@ -3785,12 +3786,15 @@ int MQTTAsync_send(MQTTAsync handle, const char* destinationName, int payloadlen
 	}
 	if ((pub->command.details.pub.destinationName = MQTTStrdup(destinationName)) == NULL)
 	{
+		free(pub);
 		rc = PAHO_MEMORY_ERROR;
 		goto exit;
 	}
 	pub->command.details.pub.payloadlen = payloadlen;
 	if ((pub->command.details.pub.payload = malloc(payloadlen)) == NULL)
 	{
+		free(pub->command.details.pub.destinationName);
+		free(pub);
 		rc = PAHO_MEMORY_ERROR;
 		goto exit;
 	}
diff --git a/src/WebSocket.c b/src/WebSocket.c
index 58f385abe919e5982dd41451cdc5cead22278c67..d116ccebd957f83605c50198e8c587fbdd4106e9 100644
--- a/src/WebSocket.c
+++ b/src/WebSocket.c
@@ -345,12 +345,14 @@ static void WebSocket_unmaskData(uint8_t *mask, size_t idx, int count, char** bu
 {
 	int i;
 
+	FUNC_ENTRY;
 	for (i = 0; i < count; ++i)
 	{
 		size_t j;
 		for ( j = 0u; j < buflens[i]; ++j, ++idx )
 			buffers[i][j] ^= mask[idx % 4];
 	}
+	FUNC_EXIT;
 }
 
 
@@ -912,9 +914,12 @@ int WebSocket_putdatas(networkHandles* net, char** buf0, size_t* buf0len,
 #endif
 			rc = Socket_putdatas(net->socket, wsdata.wsbuf0, wsdata.wsbuf0len, count, buffers, buflens, freeData);
 
-		if (mask_data)
-			WebSocket_unmaskData(wsdata.mask, *buf0len, count, buffers, buflens);
-		free(wsdata.wsbuf0); /* free temporary ws header */
+		if (rc != TCPSOCKET_INTERRUPTED)
+		{
+			if (mask_data)
+				WebSocket_unmaskData(wsdata.mask, *buf0len, count, buffers, buflens);
+			free(wsdata.wsbuf0); /* free temporary ws header */
+		}
 	}
 	else
 	{
@@ -1259,7 +1264,7 @@ int WebSocket_upgrade( networkHandles *net )
 			goto exit;
 		}
 
-		if ( rcv > 0 && strncmp( read_buf, "HTTP/1.1", 8u ) == 0 )
+		if (strncmp( read_buf, "HTTP/1.1", 8u ) == 0)
 		{
 			if (strncmp( &read_buf[9], "101", 3u ) != 0)
 			{
@@ -1269,7 +1274,7 @@ int WebSocket_upgrade( networkHandles *net )
 			}
 		}
 
-		if ( rcv > 0 && strncmp( read_buf, "HTTP/1.1 101", 12u ) == 0 )
+		if (strncmp( read_buf, "HTTP/1.1 101", 12u ) == 0)
 		{
 			const char *p;