diff --git a/README.md b/README.md
index de4ae5c..f2193df 100644
--- a/README.md
+++ b/README.md
@@ -65,7 +65,7 @@ and optional library packages are the following:
 ### Compile-time dependencies
 
 - The [css4j](https://github.com/css4j/css4j/releases) library (and its transitive
-  dependencies); version 3.9.1 or higher is recommended (compatibility with 4.0 or
+  dependencies); version 4.0 or higher is recommended (compatibility with 5.0 or
   higher is likely but not guaranteed).
 
 - The [xml-dtd](https://github.com/css4j/xml-dtd) library; version 4.1.1 or
diff --git a/RELEASE_NOTES.md b/RELEASE_NOTES.md
index 6785ce1..aac1234 100644
--- a/RELEASE_NOTES.md
+++ b/RELEASE_NOTES.md
@@ -1,6 +1,6 @@
-# css4j-agent version 3.7.1 Release Notes
+# css4j-agent version 4.0 Release Notes
 
-### January 23, 2023
+### March 30, 2023
 
 <br/>
 
@@ -14,14 +14,9 @@ Updated Public Suffix List.
 
 ## Detail of changes
 
-- Upgrade to latest public_suffix_list.dat
-- Remove unnecessary public modifier from public interfaces.
-- Javadoc: add a module description.
-- Fix javadoc warning.
-- Bump year to 2023 in copyrights.
-- Upgrade to css4j 3.9.1
-- Upgrade to slf4j-api 2.0.6
-- Upgrade to xml-dtd 4.1.1
-- Upgrade to extra-java-module-info 1.2
-- Upgrade Gradle wrapper to 7.6
-- Rename LICENSES.txt as NOTICE.txt
+- Update to latest public suffix list.
+- Upgrade to css4j 4.0
+- Upgrade to slf4j-api 2.0.7
+- Upgrade to extra-java-module-info 1.3
+- Upgrade Gradle wrapper to 8.0.2
+- Tests: convert the tests to JUnit 5.
diff --git a/build.gradle b/build.gradle
index fe2064c..f4bc6e3 100644
--- a/build.gradle
+++ b/build.gradle
@@ -5,7 +5,7 @@ plugins {
 }
 
 group = 'io.sf.carte'
-version = '3.7.2-SNAPSHOT'
+version = '4.0'
 
 description = 'css4j-agent'