diff --git a/NEWS b/NEWS
index f04d075e..d76e9024 100644
--- a/NEWS
+++ b/NEWS
@@ -1,6 +1,10 @@
-0MQ version 4.2.5 stable, released on 20xx/xx/xx
+0MQ version 4.3.1 stable, released on 20xx/xx/xx
 ================================================
 
+* The following DRAFT APIs have been marked as STABLE and will not change
+  anymore:
+  - ZMQ_MSG_T_SIZE context option (see doc/zmq_ctx_get.txt)
+
 
 0MQ version 4.2.4 stable, released on 2018/03/21
 ================================================
diff --git a/configure.ac b/configure.ac
index 216b2bc4..4a752833 100644
--- a/configure.ac
+++ b/configure.ac
@@ -42,7 +42,7 @@ AC_SUBST(PACKAGE_VERSION)
 # ZeroMQ version 4.2.2: 6:2:1 (ABI version 5)
 # ZeroMQ version 4.2.3: 6:3:1 (ABI version 5)
 # ZeroMQ version 4.2.4: 6:4:1 (ABI version 5)
-# ZeroMQ version 4.2.5: 6:5:1 (ABI version 5)
+# ZeroMQ version 4.3.1: 6:5:1 (ABI version 5)
 #
 # libzmq -version-info current:revision:age
 LTVER="6:5:1"
diff --git a/doc/zmq_ctx_get.txt b/doc/zmq_ctx_get.txt
index 74428475..10cba5af 100644
--- a/doc/zmq_ctx_get.txt
+++ b/doc/zmq_ctx_get.txt
@@ -68,7 +68,6 @@ ZMQ_MSG_T_SIZE: Get the zmq_msg_t size at runtime
 The 'ZMQ_MSG_T_SIZE' argument returns the size of the zmq_msg_t structure at
 runtime, as defined in the include/zmq.h public header.
 This is useful for example for FFI bindings that can't simply do a sizeof().
-NOTE: in DRAFT state, not yet available in stable releases.
 
 
 RETURN VALUE
diff --git a/include/zmq.h b/include/zmq.h
index 0ed1f1a3..856bd348 100644
--- a/include/zmq.h
+++ b/include/zmq.h
@@ -40,8 +40,8 @@
 
 /*  Version macros for compile-time API version detection                     */
 #define ZMQ_VERSION_MAJOR 4
-#define ZMQ_VERSION_MINOR 2
-#define ZMQ_VERSION_PATCH 5
+#define ZMQ_VERSION_MINOR 3
+#define ZMQ_VERSION_PATCH 1
 
 #define ZMQ_MAKE_VERSION(major, minor, patch)                                  \
     ((major) *10000 + (minor) *100 + (patch))
@@ -215,6 +215,7 @@ ZMQ_EXPORT void zmq_version (int *major, int *minor, int *patch);
 #define ZMQ_THREAD_PRIORITY 3
 #define ZMQ_THREAD_SCHED_POLICY 4
 #define ZMQ_MAX_MSGSZ 5
+#define ZMQ_MSG_T_SIZE 6
 
 /*  Default for new contexts                                                  */
 #define ZMQ_IO_THREADS_DFLT 1
@@ -625,7 +626,6 @@ ZMQ_EXPORT void zmq_threadclose (void *thread);
 #define ZMQ_PROTOCOL_ERROR_ZAP_INVALID_METADATA 0x20000005
 
 /*  DRAFT Context options                                                     */
-#define ZMQ_MSG_T_SIZE 6
 #define ZMQ_THREAD_AFFINITY_CPU_ADD 7
 #define ZMQ_THREAD_AFFINITY_CPU_REMOVE 8
 #define ZMQ_THREAD_NAME_PREFIX 9
diff --git a/packaging/debian/changelog b/packaging/debian/changelog
index 3cabd79f..28d3fc85 100644
--- a/packaging/debian/changelog
+++ b/packaging/debian/changelog
@@ -1,4 +1,4 @@
-zeromq (4.2.5) UNRELEASED; urgency=low
+zeromq (4.3.1) UNRELEASED; urgency=low
 
   * Initial packaging.
 
diff --git a/packaging/debian/zeromq.dsc.obs b/packaging/debian/zeromq.dsc.obs
index 5aefc859..cb53433a 100644
--- a/packaging/debian/zeromq.dsc.obs
+++ b/packaging/debian/zeromq.dsc.obs
@@ -2,7 +2,7 @@ Format: 3.0 (quilt)
 Source: zeromq
 Binary: libzmq5, libzmq3-dev, libzmq5-dbg
 Architecture: any
-Version: 4.2.5
+Version: 4.3.1
 Maintainer: libzmq Developers <zeromq-dev@lists.zeromq.org>
 Homepage: http://www.zeromq.org/
 Standards-Version: 3.9.8
diff --git a/packaging/redhat/zeromq.spec b/packaging/redhat/zeromq.spec
index f757fee3..dbec12b4 100644
--- a/packaging/redhat/zeromq.spec
+++ b/packaging/redhat/zeromq.spec
@@ -10,7 +10,7 @@
 %endif
 %define lib_name libzmq5
 Name:          zeromq
-Version:       4.2.5
+Version:       4.3.1
 Release:       1%{?dist}
 Summary:       The ZeroMQ messaging library
 Group:         Applications/Internet
diff --git a/src/zmq_draft.h b/src/zmq_draft.h
index 30d5586a..b971260f 100644
--- a/src/zmq_draft.h
+++ b/src/zmq_draft.h
@@ -96,7 +96,6 @@ unsigned long zmq_stopwatch_intermediate (void *watch_);
 #define ZMQ_PROTOCOL_ERROR_ZAP_INVALID_METADATA 0x20000005
 
 /*  DRAFT Context options                                                     */
-#define ZMQ_MSG_T_SIZE 6
 #define ZMQ_THREAD_AFFINITY_CPU_ADD 7
 #define ZMQ_THREAD_AFFINITY_CPU_REMOVE 8
 #define ZMQ_THREAD_NAME_PREFIX 9