diff --git a/CMakeLists.txt b/CMakeLists.txt
index 78a8beef1a..9ed929f771 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -9,7 +9,7 @@ project (websocketpp)
 cmake_minimum_required (VERSION 2.6)
 
 set (WEBSOCKETPP_MAJOR_VERSION 0)
-set (WEBSOCKETPP_MINOR_VERSION 3)
+set (WEBSOCKETPP_MINOR_VERSION 4)
 set (WEBSOCKETPP_PATCH_VERSION 0)
 set (WEBSOCKETPP_VERSION ${WEBSOCKETPP_MAJOR_VERSION}.${WEBSOCKETPP_MINOR_VERSION}.${WEBSOCKETPP_PATCH_VERSION})
 
diff --git a/Doxyfile b/Doxyfile
index 353a1fbd6d..f4a39ae7d4 100644
--- a/Doxyfile
+++ b/Doxyfile
@@ -33,7 +33,7 @@ PROJECT_NAME           = "websocketpp"
 # if some version control system is used.
 
 
-PROJECT_NUMBER         = "0.3.0"
+PROJECT_NUMBER         = "0.4.0-dev"
 
 
 # Using the PROJECT_BRIEF tag one can provide an optional one line description
diff --git a/readme.md b/readme.md
index 6855623194..34f2300f7b 100644
--- a/readme.md
+++ b/readme.md
@@ -1,4 +1,4 @@
-WebSocket++ (0.3.0)
+WebSocket++ (0.4.0-dev)
 ==========================
 
 WebSocket++ is a header only C++ library that implements RFC6455 The WebSocket
diff --git a/websocketpp/version.hpp b/websocketpp/version.hpp
index cf2725e48f..d6b4817330 100644
--- a/websocketpp/version.hpp
+++ b/websocketpp/version.hpp
@@ -42,7 +42,7 @@ namespace websocketpp {
 /// Library major version number
 static int const major_version = 0;
 /// Library minor version number
-static int const minor_version = 3;
+static int const minor_version = 4;
 /// Library patch version number
 static int const patch_version = 0;
 /// Library pre-release flag
@@ -50,10 +50,10 @@ static int const patch_version = 0;
  * This is a textual flag indicating the type and number for pre-release
  * versions (dev, alpha, beta, rc). This will be blank for release versions.
  */
-static char const prerelease_flag[] = "";
+static char const prerelease_flag[] = "dev";
 
 /// Default user agent string
-static char const user_agent[] = "WebSocket++/0.3.0";
+static char const user_agent[] = "WebSocket++/0.4.0-dev";
 
 } // namespace websocketpp