diff --git a/libtransmission/peer-io.c b/libtransmission/peer-io.c
index f740d0127..6d1f1e06b 100644
--- a/libtransmission/peer-io.c
+++ b/libtransmission/peer-io.c
@@ -346,6 +346,10 @@ tr_peerIoNew( tr_session       * session,
 {
     tr_peerIo * io;
 
+    assert( session != NULL );
+    assert( session->events != NULL );
+    assert( tr_amInEventThread( session ) );
+
     if( socket >= 0 )
         tr_netSetTOS( socket, session->peerSocketTOS );
 
@@ -848,6 +852,7 @@ static void
 event_enable( tr_peerIo * io, short event )
 {
     assert( tr_amInEventThread( io->session ) );
+    assert( io->session != NULL );
     assert( io->session->events != NULL );
     assert( event_initialized( &io->event_read ) );
     assert( event_initialized( &io->event_write ) );
@@ -871,6 +876,7 @@ static void
 event_disable( struct tr_peerIo * io, short event )
 {
     assert( tr_amInEventThread( io->session ) );
+    assert( io->session != NULL );
     assert( io->session->events != NULL );
     assert( event_initialized( &io->event_read ) );
     assert( event_initialized( &io->event_write ) );
diff --git a/libtransmission/trevent.c b/libtransmission/trevent.c
index 2ed25d831..3821c3445 100644
--- a/libtransmission/trevent.c
+++ b/libtransmission/trevent.c
@@ -346,8 +346,8 @@ tr_timerNew( tr_session * session,
 {
     tr_timer * timer;
 
-    assert( session );
-    assert( session->events );
+    assert( session != NULL );
+    assert( session->events != NULL );
 
     timer = tr_new0( tr_timer, 1 );
     tr_timevalMsec( interval_milliseconds, &timer->tv );
@@ -379,8 +379,8 @@ void
 tr_runInEventThread( tr_session * session,
                      void func( void* ), void * user_data )
 {
-    assert( session );
-    assert( session->events );
+    assert( session != NULL );
+    assert( session->events != NULL );
 
     if( tr_amInThread( session->events->thread ) )
     {
diff --git a/libtransmission/web.c b/libtransmission/web.c
index 622887601..cd4856987 100644
--- a/libtransmission/web.c
+++ b/libtransmission/web.c
@@ -246,6 +246,11 @@ static void
 restart_timer( tr_web * g )
 {
     struct timeval interval;
+
+    assert( tr_amInEventThread( g->session ) );
+    assert( g->session != NULL );
+    assert( g->session->events != NULL );
+
     stop_timer( g );
     dbgmsg( "adding a timeout for %ld seconds from now", g->timer_ms/1000L );
     tr_timevalMsec( g->timer_ms, &interval );
@@ -357,6 +362,11 @@ setsock( curl_socket_t            sockfd,
     const int kind = EV_PERSIST
                    | (( action & CURL_POLL_IN ) ? EV_READ : 0 )
                    | (( action & CURL_POLL_OUT ) ? EV_WRITE : 0 );
+
+    assert( tr_amInEventThread( g->session ) );
+    assert( g->session != NULL );
+    assert( g->session->events != NULL );
+
     dbgmsg( "setsock: fd is %d, curl action is %d, libevent action is %d",
             sockfd, action, kind );
     if( f->evset )