diff --git a/CMakeLists.txt b/CMakeLists.txt
index 3ce2e7d7..93abf158 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -24,13 +24,13 @@
 
 cmake_minimum_required(VERSION 3.0)
 # XXX using 1.8.90 instead of 1.9.0-DEV
-project(nghttp2 VERSION 1.30.90)
+project(nghttp2 VERSION 1.31.0)
 
 # See versioning rule:
 #  http://www.gnu.org/software/libtool/manual/html_node/Updating-version-info.html
-set(LT_CURRENT  29)
-set(LT_REVISION 2)
-set(LT_AGE      15)
+set(LT_CURRENT  30)
+set(LT_REVISION 0)
+set(LT_AGE      16)
 
 set(CMAKE_MODULE_PATH "${CMAKE_CURRENT_SOURCE_DIR}/cmake" ${CMAKE_MODULE_PATH})
 include(Version)
diff --git a/configure.ac b/configure.ac
index 8eb9ec27..9445f931 100644
--- a/configure.ac
+++ b/configure.ac
@@ -25,7 +25,7 @@ dnl Do not change user variables!
 dnl http://www.gnu.org/software/automake/manual/html_node/Flag-Variables-Ordering.html
 
 AC_PREREQ(2.61)
-AC_INIT([nghttp2], [1.31.0-DEV], [t-tujikawa@users.sourceforge.net])
+AC_INIT([nghttp2], [1.31.0], [t-tujikawa@users.sourceforge.net])
 AC_CONFIG_AUX_DIR([.])
 AC_CONFIG_MACRO_DIR([m4])
 AC_CONFIG_HEADERS([config.h])
@@ -44,9 +44,9 @@ m4_ifdef([AM_SILENT_RULES], [AM_SILENT_RULES([yes])])
 
 dnl See versioning rule:
 dnl  http://www.gnu.org/software/libtool/manual/html_node/Updating-version-info.html
-AC_SUBST(LT_CURRENT, 29)
-AC_SUBST(LT_REVISION, 2)
-AC_SUBST(LT_AGE, 15)
+AC_SUBST(LT_CURRENT, 30)
+AC_SUBST(LT_REVISION, 0)
+AC_SUBST(LT_AGE, 16)
 
 major=`echo $PACKAGE_VERSION |cut -d. -f1 | sed -e "s/[^0-9]//g"`
 minor=`echo $PACKAGE_VERSION |cut -d. -f2 | sed -e "s/[^0-9]//g"`