diff --git a/src/ws_listener.cpp b/src/ws_listener.cpp
index af04917c..d3b7221b 100644
--- a/src/ws_listener.cpp
+++ b/src/ws_listener.cpp
@@ -76,7 +76,7 @@ zmq::ws_listener_t::ws_listener_t (io_thread_t *io_thread_,
 #ifdef ZMQ_HAVE_WSS
     if (_wss) {
         int rc = gnutls_certificate_allocate_credentials (&_tls_cred);
-        assert (rc == GNUTLS_E_SUCCESS);
+        zmq_assert (rc == GNUTLS_E_SUCCESS);
 
         gnutls_datum_t cert = {(unsigned char *) options_.wss_cert_pem.c_str (),
                                (unsigned int) options_.wss_cert_pem.length ()};
@@ -84,7 +84,7 @@ zmq::ws_listener_t::ws_listener_t (io_thread_t *io_thread_,
                               (unsigned int) options_.wss_key_pem.length ()};
         rc = gnutls_certificate_set_x509_key_mem (_tls_cred, &cert, &key,
                                                   GNUTLS_X509_FMT_PEM);
-        assert (rc == GNUTLS_E_SUCCESS);
+        zmq_assert (rc == GNUTLS_E_SUCCESS);
     }
 #endif
 }
@@ -310,7 +310,7 @@ void zmq::ws_listener_t::create_engine (fd_t fd_)
           wss_engine_t (fd_, options, endpoint_pair, _address, false, _tls_cred,
                         std::string ());
 #else
-        assert (false);
+        zmq_assert (false);
 #endif
     else
         engine = new (std::nothrow)
diff --git a/src/wss_engine.cpp b/src/wss_engine.cpp
index f5a4645d..65773ad1 100644
--- a/src/wss_engine.cpp
+++ b/src/wss_engine.cpp
@@ -39,7 +39,7 @@ static int verify_certificate_callback (gnutls_session_t session)
     hostname = (const char *) gnutls_session_get_ptr (session);
 
     int rc = gnutls_certificate_verify_peers3 (session, hostname, &status);
-    assert (rc >= 0);
+    zmq_assert (rc >= 0);
 
     if (status != 0) {
         // TODO: somehow log the error
@@ -68,7 +68,7 @@ zmq::wss_engine_t::wss_engine_t (fd_t fd_,
     if (client_) {
         // TODO: move to session_base, to allow changing the socket options between connect calls
         rc = gnutls_certificate_allocate_credentials (&_tls_client_cred);
-        assert (rc == 0);
+        zmq_assert (rc == 0);
 
         if (options_.wss_trust_system)
             gnutls_certificate_set_x509_system_trust (_tls_client_cred);
@@ -79,14 +79,14 @@ zmq::wss_engine_t::wss_engine_t (fd_t fd_,
               (unsigned int) options_.wss_trust_pem.length ()};
             rc = gnutls_certificate_set_x509_trust_mem (
               _tls_client_cred, &trust, GNUTLS_X509_FMT_PEM);
-            assert (rc >= 0);
+            zmq_assert (rc >= 0);
         }
 
         gnutls_certificate_set_verify_function (_tls_client_cred,
                                                 verify_certificate_callback);
 
         rc = gnutls_init (&_tls_session, GNUTLS_CLIENT | GNUTLS_NONBLOCK);
-        assert (rc == GNUTLS_E_SUCCESS);
+        zmq_assert (rc == GNUTLS_E_SUCCESS);
 
         if (!hostname_.empty ())
             gnutls_server_name_set (_tls_session, GNUTLS_NAME_DNS,
@@ -98,16 +98,16 @@ zmq::wss_engine_t::wss_engine_t (fd_t fd_,
 
         rc = gnutls_credentials_set (_tls_session, GNUTLS_CRD_CERTIFICATE,
                                      _tls_client_cred);
-        assert (rc == GNUTLS_E_SUCCESS);
+        zmq_assert (rc == GNUTLS_E_SUCCESS);
     } else {
-        assert (tls_server_cred_);
+        zmq_assert (tls_server_cred_);
 
         rc = gnutls_init (&_tls_session, GNUTLS_SERVER | GNUTLS_NONBLOCK);
-        assert (rc == GNUTLS_E_SUCCESS);
+        zmq_assert (rc == GNUTLS_E_SUCCESS);
 
         rc = gnutls_credentials_set (_tls_session, GNUTLS_CRD_CERTIFICATE,
                                      tls_server_cred_);
-        assert (rc == GNUTLS_E_SUCCESS);
+        zmq_assert (rc == GNUTLS_E_SUCCESS);
     }
 
     gnutls_set_default_priority (_tls_session);