diff --git a/c/mqtt.c b/c/mqtt.c
index 1c4ca20..20a56af 100644
--- a/c/mqtt.c
+++ b/c/mqtt.c
@@ -131,11 +131,13 @@ typedef struct
   struct mosquitto    *mosq;                   /* mosquito structure */
   bool          is_in_use;
   bool          is_async;               /* if true then use mosquitto_connect_async */
+  int           refs;
   atom_t        symbol;                 /* <swi_mqtt>(%p) */
   bool          is_async_loop_started;  /* set to true after mosquitto_loop_start call */
   int           keepalive;
   int           loop_max_packets;
-  PL_engine_t   pl_engine;              /* prolog engine for async processing */
+  PL_engine_t   pl_engine;              /* prolog engine for async processing */  
+  bool          use_callbacks;
   predicate_t   callback_on_connect2;
   predicate_t   callback_on_disconnect2;
   predicate_t   callback_on_log2;
@@ -210,13 +212,14 @@ close_list(term_t list)
 static int
 destroy_mqtt(swi_mqtt *m)
 { 
-  _LOG("--- (f-c) destroy_mqtt swi_mqtt: %p \n", m);
-  if (m && m->mosq) {
+  _LOG("--- (f-c) destroy_mqtt swi_mqtt: %p refs: %d\n", m, m->refs);
+  if (m && m->mosq && m->refs == 0) {
     if (m->is_in_use == TRUE)
     {
       _LOG("--- (f-c) destroy_mqtt - connection is in use\n");
       return FALSE;
     } else {
+      _LOG("--- (f-c) destroy_mqtt - release mosq and blob\n");
       mosquitto_destroy(m->mosq);
       m->mosq = NULL;
       free(m);    
@@ -527,18 +530,20 @@ void on_unsubscribe_callback(struct mosquitto *mosq, void *obj, int mid)
 static void
 acquire_mqtt_symbol(atom_t symbol)
 { 
-  _LOG("--- (f-c) acquire_mqtt_symbol\n");
+  _LOG("--- (f-c) acquire_mqtt_symbol symbol: %d\n", (int) symbol);
 
   swi_mqtt *m = PL_blob_data(symbol, NULL, NULL);
   m->symbol = symbol;
+  m->refs++;
 }
 
 static int
 release_mqtt_symbol(atom_t symbol)
 { 
-  _LOG("--- (f-c) release_mqtt_symbol\n");
+  _LOG("--- (f-c) release_mqtt_symbol symbol: %d\n", (int) symbol);
 
   swi_mqtt *m = PL_blob_data(symbol, NULL, NULL);
+  m->refs--;
   destroy_mqtt(m);
   return TRUE;
 }
@@ -580,7 +585,7 @@ static int
 unify_swi_mqtt(term_t handle, swi_mqtt *m)
 {
   _LOG("--- (f-c) unify_swi_mqtt\n");
-
+  
   if ( PL_unify_blob(handle, m, sizeof(*m), &mqtt_blob) )
     return TRUE;
   if ( !PL_is_variable(handle) )
@@ -791,6 +796,7 @@ c_mqtt_pub(term_t conn, term_t topic, term_t payload, term_t options)
 
   if ( options )
   { 
+      _LOG("--- (f-c) c_mqtt_pub > parsing options...\n");
       term_t tail = PL_copy_term_ref(options);
       term_t head = PL_new_term_ref();
 
@@ -805,11 +811,12 @@ c_mqtt_pub(term_t conn, term_t topic, term_t payload, term_t options)
 
             _PL_get_arg(1, head, arg);
     
-                   if ( name == ATOM_retain) { if (!PL_get_bool(   arg, &retain)) { result = FALSE;goto CLEANUP;}
-            } else if ( name == ATOM_qos )   { if (!PL_get_integer(arg, &qos)   ) { result = FALSE;goto CLEANUP;}
+                   if ( name == ATOM_retain) { if (!PL_get_bool(   arg, &retain)) { result = FALSE;_LOG("--- (f-c) c_mqtt_pub > get ATOM_retain failed\n");goto CLEANUP;}
+            } else if ( name == ATOM_qos )   { if (!PL_get_integer(arg, &qos)   ) { result = FALSE;_LOG("--- (f-c) c_mqtt_pub > get ATOM_qos failed\n");goto CLEANUP;}
             }
     
         } else { 
+            _LOG("--- (f-c) c_mqtt_pub > PL_get_name_arity failed\n");
             result = FALSE; // pl_error("c_mqtt_pub", 4, NULL, ERR_TYPE, head, "option");
             goto CLEANUP;
         }
@@ -817,9 +824,11 @@ c_mqtt_pub(term_t conn, term_t topic, term_t payload, term_t options)
       // unify with NIL --> end of list
       if ( !PL_get_nil(tail) )
       { 
+        _LOG("--- (f-c) c_mqtt_pub > PL_get_nil failed\n");
         result = FALSE; // pl_error("c_mqtt_pub", 4, NULL, ERR_TYPE, tail, "list");
         goto CLEANUP;
       }
+      _LOG("--- (f-c) c_mqtt_pub > parsing options done\n");
   }
 
   if (!PL_get_chars(payload, &mqtt_payload, CVT_WRITE | BUF_MALLOC)) { 
@@ -932,6 +941,8 @@ c_mqtt_connect(term_t conn, term_t host, term_t port, term_t options)
     goto CLEANUP;
   }
   
+  m->refs = 0;
+
   // pass swi_mqtt as user object (will be available in all callbacks)
   mosq = mosquitto_new(client_id, true, m);
   if (mosq)
@@ -1011,6 +1022,10 @@ c_mqtt_connect(term_t conn, term_t host, term_t port, term_t options)
       }
     }
     _LOG("--- (f-c) c_mqtt_connect > bind done\n");
+  } else {
+    _LOG("--- (f-c) c_mqtt_connect > unable to create mosq client\n");
+    result = FALSE;
+    goto CLEANUP;    
   }
 
   if ( unify_swi_mqtt(conn, m) ) 
diff --git a/c/mqtt.o b/c/mqtt.o
index 9b3c9bf..aaeeae3 100644
Binary files a/c/mqtt.o and b/c/mqtt.o differ
diff --git a/lib/x86_64-linux/mqtt.so b/lib/x86_64-linux/mqtt.so
index 649785e..4208302 100644
Binary files a/lib/x86_64-linux/mqtt.so and b/lib/x86_64-linux/mqtt.so differ
diff --git a/prolog/mqtt.pl b/prolog/mqtt.pl
index 3c6a9c8..fbc07ac 100644
--- a/prolog/mqtt.pl
+++ b/prolog/mqtt.pl
@@ -99,7 +99,7 @@
 
 
 mqtt_pub(Connection, Topic, Payload) :-
-  mqtt_pub(Connection, Topic, Payload, [retain(0), qos(0)]).
+  mqtt_pub(Connection, Topic, Payload, [retain(false), qos(0)]).
 
 % publish to mqtt
 mqtt_pub(Connection, Topic, Payload, Options) :-