diff --git a/RELEASE-NOTES.md b/RELEASE-NOTES.md
index c4f509ba..dc8853f2 100644
--- a/RELEASE-NOTES.md
+++ b/RELEASE-NOTES.md
@@ -1,5 +1,24 @@
 # Release Notes
 
+## Version 4.0.1
+
+The MiniGUI development team announces the availability of MiniGUI 4.0.0.
+We strongly recommend that you use this version for any new MiniGUI
+apps, especially if the new features of MiniGUI 4.0.0 are must for your
+new apps.
+
+Please report any bugs and incompatibilities in
+
+https://github.com/VincentWei/minigui
+
+### What's new in this version
+
+This version mainly fixed some minor issues:
+
+- Use FVN algorithm to implement Str2Key.
+- Tune some API description.
+- Tune format string to use '%z' instead of '%l' or '%ll' for `size_t` values.
+
 ## Version 4.0.0
 
 The MiniGUI development team announces the availability of MiniGUI 4.0.0.
diff --git a/Version b/Version
index ab311425..4343b065 100644
--- a/Version
+++ b/Version
@@ -1,4 +1,4 @@
-Version 4.0.0 (2019/06/30)
+Version 4.0.1 (2019/07/31)
 
 This release needs the following resource packages:
 
@@ -6,4 +6,4 @@ This release needs the following resource packages:
 
 The latest samples package is:
 
-    * mg-samples-4.0.0.tar.gz
+    * mg-samples-4.0.1.tar.gz
diff --git a/configure.ac b/configure.ac
index 0e4b4efc..8312fe01 100644
--- a/configure.ac
+++ b/configure.ac
@@ -1,6 +1,6 @@
 dnl Process this file with autoconf to produce a configure script.
 AC_PREREQ(2.60)
-AC_INIT(libminigui, 4.0.0)
+AC_INIT(libminigui, 4.0.1)
 AC_CONFIG_SRCDIR(src/main/main.c)
 
 dnl Set various version strings - taken gratefully from the SDL sources
@@ -16,9 +16,9 @@ dnl Set various version strings - taken gratefully from the SDL sources
 #
 MINIGUI_MAJOR_VERSION=4
 MINIGUI_MINOR_VERSION=0
-MINIGUI_MICRO_VERSION=0
-MINIGUI_INTERFACE_AGE=0
-MINIGUI_BINARY_AGE=0
+MINIGUI_MICRO_VERSION=1
+MINIGUI_INTERFACE_AGE=1
+MINIGUI_BINARY_AGE=1
 MINIGUI_VERSION=$MINIGUI_MAJOR_VERSION.$MINIGUI_MINOR_VERSION.$MINIGUI_MICRO_VERSION
 
 AC_SUBST(MINIGUI_MAJOR_VERSION)