diff --git a/lib/mosquitto.c b/lib/mosquitto.c
index bad9402f..5009bda3 100644
--- a/lib/mosquitto.c
+++ b/lib/mosquitto.c
@@ -117,7 +117,10 @@ struct mosquitto *mosquitto_new(const char *id, bool clean_start, void *userdata
 	if(mosq){
 		mosq->sock = INVALID_SOCKET;
 #ifdef WITH_THREADING
+#  ifndef WIN32
+		/* Windows doesn't have pthread_cancel, so no need to record self */
 		mosq->thread_id = pthread_self();
+#  endif
 #endif
 		mosq->sockpairR = INVALID_SOCKET;
 		mosq->sockpairW = INVALID_SOCKET;
@@ -217,7 +220,11 @@ int mosquitto_reinitialise(struct mosquitto *mosq, const char *id, bool clean_st
 	pthread_mutex_init(&mosq->msgs_in.mutex, NULL);
 	pthread_mutex_init(&mosq->msgs_out.mutex, NULL);
 	pthread_mutex_init(&mosq->mid_mutex, NULL);
+#ifdef WIN32
+	mosq->thread_id = NULL;
+#else
 	mosq->thread_id = pthread_self();
+#endif
 #endif
 	if(mosq->disable_socketpair == false){
 		/* This must be after pthread_mutex_init(), otherwise the log mutex may be
diff --git a/lib/mosquitto_internal.h b/lib/mosquitto_internal.h
index 6f99c50f..52916fe9 100644
--- a/lib/mosquitto_internal.h
+++ b/lib/mosquitto_internal.h
@@ -329,11 +329,7 @@ struct mosquitto {
 	pthread_mutex_t out_packet_mutex;
 	pthread_mutex_t state_mutex;
 	pthread_mutex_t mid_mutex;
-#ifdef WIN32
-	int thread_id;
-#else
 	pthread_t thread_id;
-#endif
 #endif
 	bool clean_start;
 	time_t session_expiry_time;
diff --git a/lib/thread_mosq.c b/lib/thread_mosq.c
index 32a3e7e0..6b8254a7 100644
--- a/lib/thread_mosq.c
+++ b/lib/thread_mosq.c
@@ -87,7 +87,11 @@ int mosquitto_loop_stop(struct mosquitto *mosq, bool force)
 	}
 #endif
 	pthread_join(mosq->thread_id, NULL);
+#ifdef WIN32
+	mosq->thread_id = NULL;
+#else
 	mosq->thread_id = pthread_self();
+#endif
 	mosq->threaded = mosq_ts_none;
 
 	return MOSQ_ERR_SUCCESS;
diff --git a/lib/winthread_mosq.h b/lib/winthread_mosq.h
index 78743f90..ae23a133 100644
--- a/lib/winthread_mosq.h
+++ b/lib/winthread_mosq.h
@@ -33,6 +33,7 @@ typedef void pthread_condattr_t;
 
 int pthread_create(pthread_t *thread, const pthread_attr_t *attr, void *(*start_routine) (void *), void *arg);
 int pthread_join(pthread_t thread, void **retval);
+int pthread_self(void);
 int pthread_mutex_init(pthread_mutex_t *mutex, const pthread_mutexattr_t *attr);
 int pthread_mutex_destroy(pthread_mutex_t *mutex);
 int pthread_mutex_lock(pthread_mutex_t *mutex);