diff --git a/generate_api.sh b/generate_api.sh
index b98150a..f68442e 100755
--- a/generate_api.sh
+++ b/generate_api.sh
@@ -33,4 +33,5 @@ process_header nng/include/nng/protocol/survey0/respond.h >> nng_api.h
 process_header nng/include/nng/supplemental/tls/tls.h | egrep -v "nng_tls_config_(pass|key)" >> nng_api.h
 process_header nng/include/nng/transport/tls/tls.h >> nng_api.h
 
-grep '#define NNG_.*_VERSION' nng/include/nng/nng.h >> nng_api.h
+grep '^#define NNG_FLAG' nng/include/nng/nng.h >> nng_api.h
+grep '^#define NNG_.*_VERSION' nng/include/nng/nng.h >> nng_api.h
diff --git a/nng_api.h b/nng_api.h
index 876ae5b..e5cabb8 100644
--- a/nng_api.h
+++ b/nng_api.h
@@ -1,4 +1,4 @@
-// THIS FILE WAS AUTOMATICALLY GENERATED BY generate_api.sh
+// THIS FILE WAS AUTOMATICALLY GENERATED BY ./generate_api.sh
 typedef struct nng_ctx_s {
  uint32_t id;
 } nng_ctx;
@@ -276,7 +276,7 @@ extern void nng_sleep_aio(nng_duration, nng_aio *);
 extern int nng_msg_alloc(nng_msg **, size_t);
 extern void nng_msg_free(nng_msg *);
 extern int nng_msg_realloc(nng_msg *, size_t);
-extern void *nng_msg_header(nng_msg *);
+extern void * nng_msg_header(nng_msg *);
 extern size_t nng_msg_header_len(const nng_msg *);
 extern void * nng_msg_body(nng_msg *);
 extern size_t nng_msg_len(const nng_msg *);
@@ -341,10 +341,6 @@ extern int nng_pipe_id(nng_pipe);
 extern nng_socket nng_pipe_socket(nng_pipe);
 extern nng_dialer nng_pipe_dialer(nng_pipe);
 extern nng_listener nng_pipe_listener(nng_pipe);
-enum nng_flag_enum {
- NNG_FLAG_ALLOC = 1,
- NNG_FLAG_NONBLOCK = 2
-};
 extern int nng_stats_get(nng_stat **);
 extern void nng_stats_free(nng_stat *);
 extern void nng_stats_dump(nng_stat *);
@@ -545,6 +541,7 @@ int nng_pair0_open(nng_socket *);
 int nng_pair0_open_raw(nng_socket *);
 int nng_pair1_open(nng_socket *);
 int nng_pair1_open_raw(nng_socket *);
+int nng_pair1_open_poly(nng_socket *);
 int nng_push0_open(nng_socket *);
 int nng_push0_open_raw(nng_socket *);
 int nng_pull0_open(nng_socket *);
@@ -571,6 +568,12 @@ typedef enum nng_tls_auth_mode {
  NNG_TLS_AUTH_MODE_OPTIONAL = 1,
  NNG_TLS_AUTH_MODE_REQUIRED = 2,
 } nng_tls_auth_mode;
+typedef enum nng_tls_version {
+ NNG_TLS_1_0 = 0x301,
+ NNG_TLS_1_1 = 0x302,
+ NNG_TLS_1_2 = 0x303,
+ NNG_TLS_1_3 = 0x304
+} nng_tls_version;
 int nng_tls_config_alloc(nng_tls_config **, nng_tls_mode);
 void nng_tls_config_hold(nng_tls_config *);
 void nng_tls_config_free(nng_tls_config *);
@@ -583,7 +586,14 @@ int nng_tls_config_auth_mode(nng_tls_config *, nng_tls_auth_mode);
 int nng_tls_config_ca_file(nng_tls_config *, const char *);
 int nng_tls_config_cert_key_file(
     nng_tls_config *, const char *, const char *);
+int nng_tls_config_version(
+    nng_tls_config *, nng_tls_version, nng_tls_version);
+const char *nng_tls_engine_name(void);
+const char *nng_tls_engine_description(void);
+bool nng_tls_engine_fips_mode(void);
 int nng_tls_register(void);
+#define NNG_FLAG_ALLOC 1u // Recv to allocate receive buffer
+#define NNG_FLAG_NONBLOCK 2u // Non-blocking operations
 #define NNG_MAJOR_VERSION 1
-#define NNG_MINOR_VERSION 3
+#define NNG_MINOR_VERSION 4
 #define NNG_PATCH_VERSION 0
diff --git a/pynng/nng.py b/pynng/nng.py
index ba82c75..7593eab 100644
--- a/pynng/nng.py
+++ b/pynng/nng.py
@@ -692,7 +692,7 @@ class Pair0(Socket):
 
 
 class Pair1(Socket):
-    """A socket for bidrectional communication with potentially many partners.
+    """A socket for bidrectional communication with potentially many peers.
     The Python version of `nng_pair1
     <https://nanomsg.github.io/nng/man/tip/nng_pair.7>`_.
 
@@ -701,10 +701,18 @@ class Pair1(Socket):
     keyword-only argument, ``polyamorous``, which must be set to ``True`` to
     connect with more than one peer.
 
-    .. Note::
+    .. Warning::
 
         If you want to connect to multiple peers you **must** pass
-        ``polyamorous=True`` when you create your socket.
+        ``polyamorous=True`` when you create your socket.  ``polyamorous`` is a
+        read-only attribute of the socket and cannot be changed after creation.
+
+    .. Warning::
+
+        Pair1 was an experimental feature in nng, and is currently deprecated.
+        It will likely be removed in the future; see `nng's docs
+        <https://nng.nanomsg.org/man/v1.3.2/nng_pair_open.3.html>`_ for
+        details.
 
     To get the benefits of polyamory, you need to use the methods that work
     with :class:`Message` objects: :meth:`Socket.recv_msg` and
@@ -724,22 +732,24 @@ class Pair1(Socket):
 
     """
 
-    def __init__(self, *, polyamorous=None, **kwargs):
+    def __init__(self, *, polyamorous=False, **kwargs):
         # make sure we don't listen/dial before setting polyamorous, so we pop
         # them out of kwargs, then do the dial/listen below.
         # It's not beautiful, but it will work.
         dial_addr = kwargs.pop('dial', None)
         listen_addr = kwargs.pop('dial', None)
         super().__init__(**kwargs)
-        if polyamorous is not None:
-            self.polyamorous = polyamorous
+        if polyamorous:
+            self._opener = lib.nng_pair1_open_poly
+        else:
+            self._opener = lib.nng_pair1_open
         # now we can do the listen/dial
         if dial_addr is not None:
             self.dial(dial_addr, block=kwargs.get('block_on_dial'))
         if listen_addr is not None:
             self.listen(listen_addr)
 
-    _opener = lib.nng_pair1_open
+    _opener = lib.nng_pair1_open_poly
     polyamorous = BooleanOption('pair1:polyamorous')
 
 
diff --git a/setup.py b/setup.py
index b767afe..edbdba4 100644
--- a/setup.py
+++ b/setup.py
@@ -12,7 +12,7 @@
 THIS_DIR = os.path.abspath(os.path.dirname(__file__))
 
 NNG_REPO = 'https://github.com/nanomsg/nng'
-NNG_REV = '60198afcb25766a5ca060c9d3c368c4d37ad40da'
+NNG_REV = '4f5e11c391c4a8f1b2731aee5ad47bc0c925042a'
 MBEDTLS_REPO = 'https://github.com/ARMmbed/mbedtls.git'
 MBEDTLS_REV = '04a049bda1ceca48060b57bc4bcf5203ce591421'