diff --git a/takari-plugin-testing-its/pom.xml b/takari-plugin-testing-its/pom.xml
index 288a555..af1f059 100644
--- a/takari-plugin-testing-its/pom.xml
+++ b/takari-plugin-testing-its/pom.xml
@@ -143,7 +143,7 @@
                 <artifactItem>
                   <groupId>org.apache.maven</groupId>
                   <artifactId>apache-maven</artifactId>
-                  <version>4.0.0-rc-3</version>
+                  <version>4.0.0-rc-4-SNAPSHOT</version>
                   <classifier>bin</classifier>
                   <type>tar.gz</type>
                 </artifactItem>
diff --git a/takari-plugin-testing-its/src/test/java/io/takari/maven/testing/test/IntegrationTest.java b/takari-plugin-testing-its/src/test/java/io/takari/maven/testing/test/IntegrationTest.java
index ba6a017..2d810c0 100644
--- a/takari-plugin-testing-its/src/test/java/io/takari/maven/testing/test/IntegrationTest.java
+++ b/takari-plugin-testing-its/src/test/java/io/takari/maven/testing/test/IntegrationTest.java
@@ -25,8 +25,6 @@
  * <li>The test project is not able to resolve test harness from the reactor, hence the outer build
  * must run at least install phase.</li>
  * </ul>
- *
- * TODO: DOES NOT WORK WITH MAVEN 4!
  */
 @RunWith(Parameterized.class)
 public class IntegrationTest {
@@ -37,6 +35,7 @@ public static List<Object[]> versions() {
         parameters.add(new Object[] {"3.6.3"});
         parameters.add(new Object[] {"3.8.8"});
         parameters.add(new Object[] {"3.9.9"});
+        parameters.add(new Object[] {"4.0.0-rc-4-SNAPSHOT"});
         return parameters;
     }
 
diff --git a/takari-plugin-testing-its/src/test/java/io/takari/maven/testing/test/JUnit5IntegrationTests.java b/takari-plugin-testing-its/src/test/java/io/takari/maven/testing/test/JUnit5IntegrationTests.java
index c0ce745..f78156b 100644
--- a/takari-plugin-testing-its/src/test/java/io/takari/maven/testing/test/JUnit5IntegrationTests.java
+++ b/takari-plugin-testing-its/src/test/java/io/takari/maven/testing/test/JUnit5IntegrationTests.java
@@ -17,7 +17,7 @@
     "target/maven-installation/apache-maven-3.6.3",
     "target/maven-installation/apache-maven-3.8.8",
     "target/maven-installation/apache-maven-3.9.9",
-    "target/maven-installation/apache-maven-4.0.0-rc-3"
+    "target/maven-installation/apache-maven-4.0.0-rc-4-SNAPSHOT"
 })
 public class JUnit5IntegrationTests {
 
diff --git a/takari-plugin-testing-its/src/test/java/io/takari/maven/testing/test/JUnit5UnitTests.java b/takari-plugin-testing-its/src/test/java/io/takari/maven/testing/test/JUnit5UnitTests.java
index a91244a..f784776 100644
--- a/takari-plugin-testing-its/src/test/java/io/takari/maven/testing/test/JUnit5UnitTests.java
+++ b/takari-plugin-testing-its/src/test/java/io/takari/maven/testing/test/JUnit5UnitTests.java
@@ -27,8 +27,6 @@
  * <li>The test project is not able to resolve test harness from the reactor, hence the outer build
  * must run at least install phase.</li>
  * </ul>
- *
- * TODO: DOES NOT WORK WITH MAVEN 4!
  */
 class JUnit5UnitTests {
 
@@ -88,7 +86,7 @@ void testUnitTestHarnessHonoursUserSettings(MavenRuntime maven, String version)
     static final class MavenVersionsSource implements ArgumentsProvider {
 
         private List<String> getMavenVersions() {
-            return Arrays.asList("3.6.3", "3.8.8", "3.9.9");
+            return Arrays.asList("3.6.3", "3.8.8", "3.9.9", "4.0.0-rc-4-SNAPSHOT");
         }
 
         @Override
diff --git a/takari-plugin-testing-its/src/test/projects/guicescopes/pom.xml b/takari-plugin-testing-its/src/test/projects/guicescopes/pom.xml
index 1bb18d9..3705277 100644
--- a/takari-plugin-testing-its/src/test/projects/guicescopes/pom.xml
+++ b/takari-plugin-testing-its/src/test/projects/guicescopes/pom.xml
@@ -43,6 +43,12 @@
       <version>${mavenPluginPluginVersion}</version>
       <scope>provided</scope>
     </dependency>
+    <dependency>
+      <groupId>javax.inject</groupId>
+      <artifactId>javax.inject</artifactId>
+      <version>1</version>
+      <scope>provided</scope>
+    </dependency>
 
     <!-- test dependencies -->
     <dependency>
diff --git a/takari-plugin-testing/src/main/java/io/takari/maven/testing/Maven30xRuntime.java b/takari-plugin-testing/src/main/java/io/takari/maven/testing/Maven30xRuntime.java
index 712560b..4d225df 100644
--- a/takari-plugin-testing/src/main/java/io/takari/maven/testing/Maven30xRuntime.java
+++ b/takari-plugin-testing/src/main/java/io/takari/maven/testing/Maven30xRuntime.java
@@ -334,6 +334,7 @@ protected MavenExecutionRequest newExecutionRequest() throws Exception {
         systemProperties.putAll(System.getProperties()); // TODO not thread safe
         systemProperties.setProperty("maven.version", mavenVersion);
         systemProperties.setProperty("maven.build.version", mavenVersion);
+        System.getenv().forEach((k, v) -> systemProperties.setProperty("env." + k, v));
 
         // request with initial configuration
         MavenExecutionRequest request = new DefaultMavenExecutionRequest();
diff --git a/takari-plugin-testing/src/main/java/io/takari/maven/testing/executor/MavenInstallationUtils.java b/takari-plugin-testing/src/main/java/io/takari/maven/testing/executor/MavenInstallationUtils.java
index 3f29eb7..e136907 100644
--- a/takari-plugin-testing/src/main/java/io/takari/maven/testing/executor/MavenInstallationUtils.java
+++ b/takari-plugin-testing/src/main/java/io/takari/maven/testing/executor/MavenInstallationUtils.java
@@ -9,10 +9,10 @@
 
 import java.io.BufferedInputStream;
 import java.io.File;
-import java.io.FileInputStream;
 import java.io.IOException;
 import java.io.InputStream;
 import java.net.URL;
+import java.nio.file.Files;
 import java.util.Properties;
 import java.util.zip.ZipEntry;
 import java.util.zip.ZipFile;
@@ -89,7 +89,7 @@ public void addLoadFile(File file) {
                         }
                     } else {
                         try (InputStream is = new BufferedInputStream(
-                                new FileInputStream(new File(file, MAVEN_CORE_POMPROPERTIES)))) {
+                                Files.newInputStream(new File(file, MAVEN_CORE_POMPROPERTIES).toPath()))) {
                             version = getMavenVersion(is);
                         }
                     }
@@ -112,7 +112,7 @@ public void addLoadURL(URL url) {}
             properties.setProperty(SYSPROP_MAVEN_MAIN_CLASS, MAVEN4_MAIN_CLASS); // must for maven4, ignored by maven3
             properties.setProperty(SYSPROP_MAVEN_HOME, mavenHome.getCanonicalPath());
             ConfigurationParser configParser = new ConfigurationParser(configHandler, properties);
-            try (InputStream is = new BufferedInputStream(new FileInputStream(classworldsConf))) {
+            try (InputStream is = new BufferedInputStream(Files.newInputStream(classworldsConf.toPath()))) {
                 configParser.parse(is);
             }
         } catch (IOException | ClassWorldException | ConfigurationException e) {
diff --git a/takari-plugin-testing/src/main/java/io/takari/maven/testing/executor/MavenRuntime.java b/takari-plugin-testing/src/main/java/io/takari/maven/testing/executor/MavenRuntime.java
index e952241..2a4f9df 100644
--- a/takari-plugin-testing/src/main/java/io/takari/maven/testing/executor/MavenRuntime.java
+++ b/takari-plugin-testing/src/main/java/io/takari/maven/testing/executor/MavenRuntime.java
@@ -124,7 +124,7 @@ public MavenRuntime build() throws Exception {
 
     public static class ForkedMavenRuntimeBuilder extends MavenRuntimeBuilder {
 
-        private Map<String, String> environment;
+        private Map<String, String> environment = new HashMap<>(System.getenv());
         private final List<String> jvmArgs = new ArrayList<>();
 
         ForkedMavenRuntimeBuilder(File mavenHome, File classworldsConf) {
diff --git a/takari-plugin-testing/src/main/java/io/takari/maven/testing/executor/junit/MavenInstallationsTestExtension.java b/takari-plugin-testing/src/main/java/io/takari/maven/testing/executor/junit/MavenInstallationsTestExtension.java
index 4da0628..c10c133 100644
--- a/takari-plugin-testing/src/main/java/io/takari/maven/testing/executor/junit/MavenInstallationsTestExtension.java
+++ b/takari-plugin-testing/src/main/java/io/takari/maven/testing/executor/junit/MavenInstallationsTestExtension.java
@@ -41,7 +41,7 @@ public boolean supportsTestTemplate(ExtensionContext context) {
     public Stream<TestTemplateInvocationContext> provideTestTemplateInvocationContexts(ExtensionContext context) {
         String displayName = context.getDisplayName();
         String[] installations = context.getTestClass()
-                .orElseThrow()
+                .orElseThrow(IllegalStateException::new)
                 .getAnnotation(MavenInstallations.class)
                 .value();
         return Arrays.stream(installations)
diff --git a/takari-plugin-testing/src/main/java/io/takari/maven/testing/executor/junit/MavenVersionsTestExtension.java b/takari-plugin-testing/src/main/java/io/takari/maven/testing/executor/junit/MavenVersionsTestExtension.java
index 3c06219..6a123a7 100644
--- a/takari-plugin-testing/src/main/java/io/takari/maven/testing/executor/junit/MavenVersionsTestExtension.java
+++ b/takari-plugin-testing/src/main/java/io/takari/maven/testing/executor/junit/MavenVersionsTestExtension.java
@@ -45,7 +45,7 @@ public boolean supportsTestTemplate(ExtensionContext context) {
     public Stream<TestTemplateInvocationContext> provideTestTemplateInvocationContexts(ExtensionContext context) {
         String displayName = context.getDisplayName();
         String[] versions = context.getTestClass()
-                .orElseThrow()
+                .orElseThrow(IllegalStateException::new)
                 .getAnnotation(MavenVersions.class)
                 .value();
         List<TestTemplateInvocationContext> contexts = new ArrayList<>();