diff --git a/.github/workflows/maven-build.yml b/.github/workflows/maven-build.yml
index a2d20ca..470baeb 100644
--- a/.github/workflows/maven-build.yml
+++ b/.github/workflows/maven-build.yml
@@ -14,7 +14,7 @@ jobs:
     runs-on: ubuntu-latest
     strategy:
       matrix:
-        java: [ 8, 11 ]
+        java: [ 8, 11, 13 ]
     steps:
       - uses: actions/checkout@v2
       - name: Set up JDK ${{ matrix.java }}
diff --git a/CHANGELOG.org b/CHANGELOG.org
index 5f19b75..379f6ec 100644
--- a/CHANGELOG.org
+++ b/CHANGELOG.org
@@ -10,11 +10,11 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 ** Added
 
 - Add kemitix-maven-tiles 2.4.1
+- Tests run against JDK 8, 11 and 13 (#62)
 
 ** Changed
 
 - Moved: Node.drawTree to Nodes (#60)
-- Pinned pitest-junit5-plugin at 0.9 (#59)
 - Replace Jenkins with Github Actions (#57)
 - [checkstyle] suppress npath complexity issues
 - [coverage] lower requirements
diff --git a/pom.xml b/pom.xml
index de0d4da..b3a445e 100644
--- a/pom.xml
+++ b/pom.xml
@@ -21,7 +21,6 @@
         <maven.compiler.target>${java.version}</maven.compiler.target>
         <tiles-maven-plugin.version>2.16</tiles-maven-plugin.version>
         <kemitix-maven-tiles.version>2.4.1</kemitix-maven-tiles.version>
-        <pitest-junit5-plugin.version>0.9</pitest-junit5-plugin.version>
         <kemitix-checkstyle.version>5.4.0</kemitix-checkstyle.version>
         <lombok.version>1.18.12</lombok.version>
         <assertj.version>3.15.0</assertj.version>
diff --git a/src/test/java/net/kemitix/node/ImmutableNodeItemTest.java b/src/test/java/net/kemitix/node/ImmutableNodeItemTest.java
index 64aaa69..6a1bf11 100644
--- a/src/test/java/net/kemitix/node/ImmutableNodeItemTest.java
+++ b/src/test/java/net/kemitix/node/ImmutableNodeItemTest.java
@@ -12,7 +12,9 @@ import java.util.Optional;
 import java.util.stream.Collectors;
 import java.util.stream.Stream;
 
-import static org.assertj.core.api.Assertions.*;
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.assertj.core.api.Assertions.assertThatExceptionOfType;
+import static org.assertj.core.api.Assertions.assertThatNullPointerException;
 
 /**
  * Test for {@link ImmutableNodeItem}.
diff --git a/src/test/java/net/kemitix/node/NodeItemTest.java b/src/test/java/net/kemitix/node/NodeItemTest.java
index 7aa5158..51d3789 100644
--- a/src/test/java/net/kemitix/node/NodeItemTest.java
+++ b/src/test/java/net/kemitix/node/NodeItemTest.java
@@ -12,7 +12,9 @@ import java.util.Optional;
 import java.util.Set;
 import java.util.stream.Collectors;
 
-import static org.assertj.core.api.Assertions.*;
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.assertj.core.api.Assertions.assertThatExceptionOfType;
+import static org.assertj.core.api.Assertions.assertThatNullPointerException;
 
 /**
  * Test for {@link NodeItem}.