diff --git a/src/pgm_sender.cpp b/src/pgm_sender.cpp
index 759802f8..1a1ae9a9 100644
--- a/src/pgm_sender.cpp
+++ b/src/pgm_sender.cpp
@@ -98,8 +98,8 @@ void zmq::pgm_sender_t::plug (io_thread_t *io_thread_, session_base_t *session_)
     msg_t msg;
     msg.init_size (1);
     *(unsigned char*) msg.data () = 1;
-    bool ok = session_->write (&msg);
-    zmq_assert (ok);
+    int rc = session_->write (&msg);
+    errno_assert (rc == 0);
     session_->flush ();
 }