diff --git a/CMakeLists.txt b/CMakeLists.txt
index d19492f..8cbd789 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -16,7 +16,7 @@
 
 cmake_minimum_required(VERSION 3.1...3.5)
 
-project(SPTK VERSION 4.1)
+project(SPTK VERSION 4.2)
 
 if (CMAKE_CXX_COMPILER_ID MATCHES "Clang")
   if(CMAKE_CXX_COMPILER_VERSION VERSION_LESS 3.5.0)
diff --git a/README.md b/README.md
index b9b8ff6..f7fb050 100644
--- a/README.md
+++ b/README.md
@@ -6,7 +6,7 @@ The Speech Signal Processing Toolkit (SPTK) is a software for speech signal proc
 - PyTorch version: [diffsptk](https://github.com/sp-nitech/diffsptk)
 
 [![](https://img.shields.io/badge/docs-latest-blue.svg)](https://sp-nitech.github.io/sptk/latest/)
-[![](https://img.shields.io/badge/docs-stable-blue.svg)](https://sp-nitech.github.io/sptk/4.1/)
+[![](https://img.shields.io/badge/docs-stable-blue.svg)](https://sp-nitech.github.io/sptk/4.2/)
 [![](https://img.shields.io/badge/license-Apache%202.0-green.svg)](https://github.com/sp-nitech/SPTK/blob/master/LICENSE)
 [![](https://github.com/sp-nitech/SPTK/workflows/build/badge.svg)](https://github.com/sp-nitech/SPTK/actions)
 
diff --git a/include/SPTK/utils/sptk_utils.h b/include/SPTK/utils/sptk_utils.h
index 712152b..38db3f6 100644
--- a/include/SPTK/utils/sptk_utils.h
+++ b/include/SPTK/utils/sptk_utils.h
@@ -36,7 +36,7 @@
 namespace sptk {
 
 //! Version of SPTK.
-static const char* const kVersion("4.1");
+static const char* const kVersion("4.2");
 //! @f$\pi@f$
 static const double kPi(3.141592653589793);
 //! @f$2\pi@f$