diff --git a/pitest-command-line/src/main/java/org/pitest/mutationtest/commandline/ParseResult.java b/pitest-command-line/src/main/java/org/pitest/mutationtest/commandline/ParseResult.java
index eab29e2e1..895dce83b 100644
--- a/pitest-command-line/src/main/java/org/pitest/mutationtest/commandline/ParseResult.java
+++ b/pitest-command-line/src/main/java/org/pitest/mutationtest/commandline/ParseResult.java
@@ -28,7 +28,7 @@ public ParseResult(final ReportOptions options, final String errorMessage) {
   }
 
   public boolean isOk() {
-    return !this.errorMessage.isPresent();
+    return this.errorMessage.isEmpty();
   }
 
   public ReportOptions getOptions() {
diff --git a/pitest-command-line/src/test/java/org/pitest/mutationtest/commandline/OptionsParserTest.java b/pitest-command-line/src/test/java/org/pitest/mutationtest/commandline/OptionsParserTest.java
index fdce204a8..46c9a39ff 100644
--- a/pitest-command-line/src/test/java/org/pitest/mutationtest/commandline/OptionsParserTest.java
+++ b/pitest-command-line/src/test/java/org/pitest/mutationtest/commandline/OptionsParserTest.java
@@ -27,7 +27,7 @@
 import java.io.File;
 import java.nio.charset.Charset;
 import java.nio.charset.StandardCharsets;
-import java.nio.file.Paths;
+import java.nio.file.Path;
 import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.Collection;
@@ -94,7 +94,7 @@ public void shouldCreatePredicateFromCommaSeparatedListOfTargetClassGlobs() {
   public void shouldParseCommaSeparatedListOfSourceDirectories() {
     final ReportOptions actual = parseAddingRequiredArgs("--sourceDirs",
         "foo/bar,bar/far");
-    assertThat(actual.getSourcePaths()).containsExactly(Paths.get("foo/bar"), Paths.get(("bar/far")));
+    assertThat(actual.getSourcePaths()).containsExactly(Path.of("foo/bar"), Path.of(("bar/far")));
   }
 
   @Test
diff --git a/pitest-entry/src/main/java/org/pitest/classinfo/ClassInfo.java b/pitest-entry/src/main/java/org/pitest/classinfo/ClassInfo.java
index 5ec45fbf7..83b13315c 100644
--- a/pitest-entry/src/main/java/org/pitest/classinfo/ClassInfo.java
+++ b/pitest-entry/src/main/java/org/pitest/classinfo/ClassInfo.java
@@ -88,7 +88,7 @@ private Optional<ClassInfo> getParent() {
 
   private boolean descendsFrom(final ClassName clazz) {
 
-    if (!this.getSuperClass().isPresent()) {
+    if (this.getSuperClass().isEmpty()) {
       return false;
     }
 
diff --git a/pitest-entry/src/main/java/org/pitest/coverage/execute/CoverageProcess.java b/pitest-entry/src/main/java/org/pitest/coverage/execute/CoverageProcess.java
index 7644446c8..9a9efd338 100644
--- a/pitest-entry/src/main/java/org/pitest/coverage/execute/CoverageProcess.java
+++ b/pitest-entry/src/main/java/org/pitest/coverage/execute/CoverageProcess.java
@@ -34,7 +34,7 @@ public void start() throws IOException, InterruptedException {
   public ExitCode waitToDie() {
     try {
       Optional<ExitCode> maybeExit = this.crt.waitToFinish(5);
-      while (!maybeExit.isPresent() && this.process.isAlive()) {
+      while (maybeExit.isEmpty() && this.process.isAlive()) {
         maybeExit = this.crt.waitToFinish(10);
       }
 
diff --git a/pitest-entry/src/main/java/org/pitest/mutationtest/build/intercept/RegionInterceptor.java b/pitest-entry/src/main/java/org/pitest/mutationtest/build/intercept/RegionInterceptor.java
index 50a8db0be..b7e68c783 100644
--- a/pitest-entry/src/main/java/org/pitest/mutationtest/build/intercept/RegionInterceptor.java
+++ b/pitest-entry/src/main/java/org/pitest/mutationtest/build/intercept/RegionInterceptor.java
@@ -47,7 +47,7 @@ protected Predicate<MutationDetails> buildPredicate() {
             final int instruction = a.getInstructionIndex();
             final Optional<MethodTree> method = this.currentClass.method(a.getId().getLocation());
 
-            if (!method.isPresent()) {
+            if (method.isEmpty()) {
                 return false;
             }
 
diff --git a/pitest-entry/src/main/java/org/pitest/mutationtest/build/intercept/annotations/ExcludedAnnotationInterceptor.java b/pitest-entry/src/main/java/org/pitest/mutationtest/build/intercept/annotations/ExcludedAnnotationInterceptor.java
index 8d228c0b2..a8808fdd4 100644
--- a/pitest-entry/src/main/java/org/pitest/mutationtest/build/intercept/annotations/ExcludedAnnotationInterceptor.java
+++ b/pitest-entry/src/main/java/org/pitest/mutationtest/build/intercept/annotations/ExcludedAnnotationInterceptor.java
@@ -97,8 +97,7 @@ private void collectLambdaMethods(MethodTree method, ClassTree clazz,
 
       List<MethodTree> recurse = lambdas.stream()
               .map(clazz::method)
-              .filter(Optional::isPresent)
-              .map(Optional::get)
+              .flatMap(Optional::stream)
               .collect(Collectors.toList());
 
       methodsToProcess.addAll(recurse);
diff --git a/pitest-entry/src/main/java/org/pitest/mutationtest/build/intercept/javafeatures/ForEachLoopFilter.java b/pitest-entry/src/main/java/org/pitest/mutationtest/build/intercept/javafeatures/ForEachLoopFilter.java
index 26bddc9b9..b4b242479 100644
--- a/pitest-entry/src/main/java/org/pitest/mutationtest/build/intercept/javafeatures/ForEachLoopFilter.java
+++ b/pitest-entry/src/main/java/org/pitest/mutationtest/build/intercept/javafeatures/ForEachLoopFilter.java
@@ -191,7 +191,7 @@ private Predicate<MutationDetails> mutatesIteratorLoopPlumbing() {
     return a -> {
       final int instruction = a.getInstructionIndex();
       final Optional<MethodTree> maybeMethod = currentClass.method(a.getId().getLocation());
-      if (!maybeMethod.isPresent()) {
+      if (maybeMethod.isEmpty()) {
         return false;
       }
       MethodTree method = maybeMethod.get();
diff --git a/pitest-entry/src/main/java/org/pitest/mutationtest/build/intercept/javafeatures/InlinedFinallyBlockFilter.java b/pitest-entry/src/main/java/org/pitest/mutationtest/build/intercept/javafeatures/InlinedFinallyBlockFilter.java
index 9216718cb..e16bde277 100644
--- a/pitest-entry/src/main/java/org/pitest/mutationtest/build/intercept/javafeatures/InlinedFinallyBlockFilter.java
+++ b/pitest-entry/src/main/java/org/pitest/mutationtest/build/intercept/javafeatures/InlinedFinallyBlockFilter.java
@@ -171,7 +171,7 @@ private void checkForInlinedCode(Collection<MutationDetails> mutantsToReturn,
 
   private boolean isInFinallyBlock(MutationDetails m) {
     Optional<MethodTree> maybeMethod = currentClass.method(m.getId().getLocation());
-    if (!maybeMethod.isPresent()) {
+    if (maybeMethod.isEmpty()) {
       return false;
     }
     MethodTree method = maybeMethod.get();
diff --git a/pitest-entry/src/main/java/org/pitest/mutationtest/build/intercept/timeout/AvoidForLoopCounterFilter.java b/pitest-entry/src/main/java/org/pitest/mutationtest/build/intercept/timeout/AvoidForLoopCounterFilter.java
index c9c38c837..5bb77cf7e 100644
--- a/pitest-entry/src/main/java/org/pitest/mutationtest/build/intercept/timeout/AvoidForLoopCounterFilter.java
+++ b/pitest-entry/src/main/java/org/pitest/mutationtest/build/intercept/timeout/AvoidForLoopCounterFilter.java
@@ -160,7 +160,7 @@ private Predicate<MutationDetails> mutatesAForLoopCounter() {
     return a -> {
       final int instruction = a.getInstructionIndex();
       Optional<MethodTree> maybeMethod = AvoidForLoopCounterFilter.this.currentClass.method(a.getId().getLocation());
-      if (!maybeMethod.isPresent()) {
+      if (maybeMethod.isEmpty()) {
         return false;
       }
       MethodTree method = maybeMethod.get();
@@ -182,8 +182,7 @@ private Set<AbstractInsnNode> findLoopCounters(MethodTree method) {
     Context context = Context.start(DEBUG);
     return MUTATED_FOR_COUNTER.contextMatches(method.instructions(), context).stream()
             .map(c -> c.retrieve(MUTATED_INSTRUCTION.read()))
-            .filter(Optional::isPresent)
-            .map(Optional::get)
+            .flatMap(Optional::stream)
             .collect(Collectors.toSet());
   }
 
diff --git a/pitest-entry/src/main/java/org/pitest/mutationtest/build/intercept/timeout/InfiniteLoopFilter.java b/pitest-entry/src/main/java/org/pitest/mutationtest/build/intercept/timeout/InfiniteLoopFilter.java
index 254531013..87f77f2fc 100644
--- a/pitest-entry/src/main/java/org/pitest/mutationtest/build/intercept/timeout/InfiniteLoopFilter.java
+++ b/pitest-entry/src/main/java/org/pitest/mutationtest/build/intercept/timeout/InfiniteLoopFilter.java
@@ -56,7 +56,7 @@ private Collection<MutationDetails> findTimeoutMutants(Location location,
       Collection<MutationDetails> mutations, Mutater m) {
 
     final Optional<MethodTree> maybeMethod = this.currentClass.method(location);
-    if (!maybeMethod.isPresent()) {
+    if (maybeMethod.isEmpty()) {
       return Collections.emptyList();
     }
     MethodTree method = maybeMethod.get();
diff --git a/pitest-entry/src/main/java/org/pitest/mutationtest/execute/MutationTestProcess.java b/pitest-entry/src/main/java/org/pitest/mutationtest/execute/MutationTestProcess.java
index a79667c73..fe39b7dc8 100644
--- a/pitest-entry/src/main/java/org/pitest/mutationtest/execute/MutationTestProcess.java
+++ b/pitest-entry/src/main/java/org/pitest/mutationtest/execute/MutationTestProcess.java
@@ -57,7 +57,7 @@ public ExitCode waitToDie() {
 
       // While the monitored process reports being alive, keep polling
       // the monitoring thread to see if it has finished.
-      while (!maybeExit.isPresent() && this.process.isAlive()) {
+      while (maybeExit.isEmpty() && this.process.isAlive()) {
         maybeExit = this.thread.waitToFinish(10);
       }
 
diff --git a/pitest-entry/src/main/java/org/pitest/mutationtest/incremental/IncrementalAnalyser.java b/pitest-entry/src/main/java/org/pitest/mutationtest/incremental/IncrementalAnalyser.java
index 57f0d8ef9..2b3d789a1 100644
--- a/pitest-entry/src/main/java/org/pitest/mutationtest/incremental/IncrementalAnalyser.java
+++ b/pitest-entry/src/main/java/org/pitest/mutationtest/incremental/IncrementalAnalyser.java
@@ -136,7 +136,7 @@ private MutationResult prioritiseLastTest(MutationDetails mutation, String killi
             .findFirst();
 
     // last killing test is no longer available
-    if (!maybeKillingTest.isPresent()) {
+    if (maybeKillingTest.isEmpty()) {
       return analyseFromScratch(mutation);
     }
 
diff --git a/pitest-entry/src/main/java/org/pitest/mutationtest/tooling/EntryPoint.java b/pitest-entry/src/main/java/org/pitest/mutationtest/tooling/EntryPoint.java
index 7b7d46256..c83c6ad63 100644
--- a/pitest-entry/src/main/java/org/pitest/mutationtest/tooling/EntryPoint.java
+++ b/pitest-entry/src/main/java/org/pitest/mutationtest/tooling/EntryPoint.java
@@ -157,7 +157,7 @@ private void updateData(ReportOptions data, SettingsFactory settings) {
 
   private History pickHistoryStore(CodeSource code, ReportOptions data, Optional<WriterFactory> historyWriter, HistoryFactory factory) {
     final Optional<Reader> reader = data.createHistoryReader();
-    if (!reader.isPresent() && !historyWriter.isPresent()) {
+    if (reader.isEmpty() && historyWriter.isEmpty()) {
       return new NullHistory();
     }
     FeatureParser parser = new FeatureParser();
diff --git a/pitest-entry/src/main/java/org/pitest/mutationtest/tooling/JarCreatingJarFinder.java b/pitest-entry/src/main/java/org/pitest/mutationtest/tooling/JarCreatingJarFinder.java
index ca8930843..e337679b4 100644
--- a/pitest-entry/src/main/java/org/pitest/mutationtest/tooling/JarCreatingJarFinder.java
+++ b/pitest-entry/src/main/java/org/pitest/mutationtest/tooling/JarCreatingJarFinder.java
@@ -59,7 +59,7 @@ public JarCreatingJarFinder() {
 
   @Override
   public Optional<String> getJarLocation() {
-    if (!this.location.isPresent()) {
+    if (this.location.isEmpty()) {
       this.location = createJar();
     }
     return this.location;
diff --git a/pitest-entry/src/main/java/org/pitest/util/FileUtil.java b/pitest-entry/src/main/java/org/pitest/util/FileUtil.java
index 3b252dfc8..09f2d470e 100644
--- a/pitest-entry/src/main/java/org/pitest/util/FileUtil.java
+++ b/pitest-entry/src/main/java/org/pitest/util/FileUtil.java
@@ -3,6 +3,7 @@
 import java.io.BufferedReader;
 import java.io.InputStream;
 import java.io.InputStreamReader;
+import java.util.concurrent.ThreadLocalRandom;
 
 public class FileUtil {
 
@@ -24,7 +25,7 @@ public static String readToString(final InputStream is)
 
   public static String randomFilename() {
     return System.currentTimeMillis()
-        + ("" + Math.random()).replaceAll("\\.", "");
+        + ("" + ThreadLocalRandom.current().nextDouble()).replaceAll("\\.", "");
   }
 
 }
diff --git a/pitest-entry/src/test/java/org/pitest/mutationtest/incremental/IncrementalAnalyserTest.java b/pitest-entry/src/test/java/org/pitest/mutationtest/incremental/IncrementalAnalyserTest.java
index 5bdecc776..3f1038f43 100644
--- a/pitest-entry/src/test/java/org/pitest/mutationtest/incremental/IncrementalAnalyserTest.java
+++ b/pitest-entry/src/test/java/org/pitest/mutationtest/incremental/IncrementalAnalyserTest.java
@@ -386,7 +386,7 @@ public void describeTo(final Description description) {
       protected boolean matchesSafely(final MutationResult item,
                                       final Description mismatchDescription) {
         Optional<String> itemKillingTest = item.getKillingTest();
-        if (!itemKillingTest.isPresent()) {
+        if (itemKillingTest.isEmpty()) {
           mismatchDescription
                   .appendText("a mutation result with no killing test");
           return false;
diff --git a/pitest-maven/src/main/java/org/pitest/maven/MojoToReportOptionsConverter.java b/pitest-maven/src/main/java/org/pitest/maven/MojoToReportOptionsConverter.java
index 1f9c98b8b..5ba91a12c 100644
--- a/pitest-maven/src/main/java/org/pitest/maven/MojoToReportOptionsConverter.java
+++ b/pitest-maven/src/main/java/org/pitest/maven/MojoToReportOptionsConverter.java
@@ -136,7 +136,7 @@ private void autoAddJUnitPlatform(List<String> classPath) {
     }
 
     Optional<Artifact> maybeJUnitPlatform = findJUnitArtifact(junitDependencies);
-    if (!maybeJUnitPlatform.isPresent()) {
+    if (maybeJUnitPlatform.isEmpty()) {
       this.log.debug("JUnit 5 not on classpath");
       return;
     }
diff --git a/pitest-maven/src/test/java/org/pitest/maven/MojoToReportOptionsConverterTest.java b/pitest-maven/src/test/java/org/pitest/maven/MojoToReportOptionsConverterTest.java
index 5e20c7ac9..1c910c5b0 100644
--- a/pitest-maven/src/test/java/org/pitest/maven/MojoToReportOptionsConverterTest.java
+++ b/pitest-maven/src/test/java/org/pitest/maven/MojoToReportOptionsConverterTest.java
@@ -29,7 +29,7 @@
 
 import java.io.File;
 import java.nio.charset.StandardCharsets;
-import java.nio.file.Paths;
+import java.nio.file.Path;
 import java.util.ArrayList;
 import java.util.Collection;
 import java.util.Collections;
@@ -95,7 +95,7 @@ public void testUsesSourceDirectoriesFromProject() {
     when(this.project.getTestCompileSourceRoots()).thenReturn(
         asList("tst"));
     final ReportOptions actual = parseConfig("");
-    assertThat(actual.getSourcePaths()).containsExactly(Paths.get("src"), Paths.get("tst"));
+    assertThat(actual.getSourcePaths()).containsExactly(Path.of("src"), Path.of("tst"));
   }
 
   public void testParsesExcludedRunners() {
diff --git a/pitest/src/main/java/org/pitest/classinfo/ComputeClassWriter.java b/pitest/src/main/java/org/pitest/classinfo/ComputeClassWriter.java
index 913eb522f..bafb45bad 100644
--- a/pitest/src/main/java/org/pitest/classinfo/ComputeClassWriter.java
+++ b/pitest/src/main/java/org/pitest/classinfo/ComputeClassWriter.java
@@ -186,7 +186,7 @@ private boolean typeImplements(String type, ClassReader info, final String itf)
    */
   private ClassReader typeInfo(final String type) {
     final Optional<byte[]> maybeBytes = this.bytes.getBytes(type);
-    if (!maybeBytes.isPresent()) {
+    if (maybeBytes.isEmpty()) {
       throw new PitError("Could not find class definition for " + type);
     }
     return new ClassReader(maybeBytes.get());
diff --git a/pitest/src/main/java/org/pitest/mutationtest/config/PrioritisingTestConfiguration.java b/pitest/src/main/java/org/pitest/mutationtest/config/PrioritisingTestConfiguration.java
index 9827308cf..5c8428f98 100644
--- a/pitest/src/main/java/org/pitest/mutationtest/config/PrioritisingTestConfiguration.java
+++ b/pitest/src/main/java/org/pitest/mutationtest/config/PrioritisingTestConfiguration.java
@@ -41,7 +41,7 @@ public Optional<PitHelpError> verifyEnvironment() {
 
     private static List<Configuration> pickChildren(List<Configuration> configs) {
         List<Configuration> working = configs.stream()
-                .filter(c -> !c.verifyEnvironment().isPresent())
+                .filter(c -> c.verifyEnvironment().isEmpty())
                 .sorted(byPriority())
                 .collect(Collectors.toList());
         // We don't have a working config, let it report errors later