diff --git a/.github/workflows/build.yml b/.github/workflows/build.yml
index 40c70094da..b1c034a14f 100644
--- a/.github/workflows/build.yml
+++ b/.github/workflows/build.yml
@@ -164,6 +164,8 @@ jobs:
             java: 11
           - suite: caffeine:weakKeysAndSoftValuesSyncGuavaTest
             java: 11
+          - suite: caffeine:fuzzTest
+            java: 11
     env:
       JAVA_VERSION: ${{ matrix.java }}
     steps:
diff --git a/.gitignore b/.gitignore
index 36105135e5..b786d47257 100644
--- a/.gitignore
+++ b/.gitignore
@@ -6,6 +6,7 @@ build-cache
 test-output
 jitwatch.out
 .DS_Store
+.cifuzz-corpus
 .classpath
 .settings
 .project
diff --git a/caffeine/build.gradle.kts b/caffeine/build.gradle.kts
index f938a9466a..3796d58143 100644
--- a/caffeine/build.gradle.kts
+++ b/caffeine/build.gradle.kts
@@ -31,6 +31,7 @@ dependencies {
   testImplementation(libs.ycsb) {
     isTransitive = false
   }
+  testImplementation(libs.jazzer)
   testImplementation(libs.picocli)
   testImplementation(libs.jctools)
   testImplementation(libs.fastutil)
@@ -152,6 +153,18 @@ tasks.register<Test>("lincheckTest") {
   }
 }
 
+tasks.register<Test>("fuzzTest") {
+  group = "Verification"
+  description = "Fuzz tests"
+
+  forkEvery = 1
+  failFast = true
+  useJUnitPlatform()
+  testLogging.events("started")
+  environment("JAZZER_FUZZ", "1")
+  include("com/github/benmanes/caffeine/fuzz/**")
+}
+
 val junitTest = tasks.register<Test>("junitTest") {
   group = "Verification"
   description = "JUnit tests"
@@ -162,6 +175,7 @@ val junitTest = tasks.register<Test>("junitTest") {
   useJUnit()
   failFast = true
   maxHeapSize = "2g"
+  exclude("com/github/benmanes/caffeine/fuzz/**")
   systemProperty("caffeine.osgi.jar", relativePath(jar.get().archiveFile.get().asFile.path))
 }
 
diff --git a/caffeine/src/main/java/com/github/benmanes/caffeine/cache/CaffeineSpec.java b/caffeine/src/main/java/com/github/benmanes/caffeine/cache/CaffeineSpec.java
index 6f280d1bae..08edd68e7f 100644
--- a/caffeine/src/main/java/com/github/benmanes/caffeine/cache/CaffeineSpec.java
+++ b/caffeine/src/main/java/com/github/benmanes/caffeine/cache/CaffeineSpec.java
@@ -156,7 +156,7 @@ void parseOption(String option) {
 
     @SuppressWarnings("StringSplitter")
     String[] keyAndValue = option.split(SPLIT_KEY_VALUE);
-    requireArgument(keyAndValue.length <= 2,
+    requireArgument((keyAndValue.length >= 1) && (keyAndValue.length <= 2),
         "key-value pair %s with more than one equals sign", option);
 
     String key = keyAndValue[0].trim();
diff --git a/caffeine/src/test/java/com/github/benmanes/caffeine/fuzz/CaffeineSpecFuzzer.java b/caffeine/src/test/java/com/github/benmanes/caffeine/fuzz/CaffeineSpecFuzzer.java
new file mode 100644
index 0000000000..30f5a411ff
--- /dev/null
+++ b/caffeine/src/test/java/com/github/benmanes/caffeine/fuzz/CaffeineSpecFuzzer.java
@@ -0,0 +1,36 @@
+/*
+ * Copyright 2024 Ben Manes. All Rights Reserved.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package com.github.benmanes.caffeine.fuzz;
+
+import com.code_intelligence.jazzer.api.FuzzedDataProvider;
+import com.code_intelligence.jazzer.junit.FuzzTest;
+import com.github.benmanes.caffeine.cache.CaffeineSpec;
+
+/**
+ * @author ben.manes@gmail.com (Ben Manes)
+ */
+public final class CaffeineSpecFuzzer {
+
+  // These tests require the environment variable JAZZER_FUZZ=1 to try new input arguments
+
+  @FuzzTest(maxDuration = "5m")
+  @SuppressWarnings("CheckReturnValue")
+  public void parse(FuzzedDataProvider data) {
+    try {
+      CaffeineSpec.parse(data.consumeRemainingAsString());
+    } catch (IllegalArgumentException e) { /* ignored */ }
+  }
+}
diff --git a/gradle/libs.versions.toml b/gradle/libs.versions.toml
index 7060f4fd62..801f927547 100644
--- a/gradle/libs.versions.toml
+++ b/gradle/libs.versions.toml
@@ -49,6 +49,7 @@ jakarta-inject = "2.0.1"
 jamm = "0.4.0"
 java-object-layout = "0.17"
 javapoet = "1.13.0"
+jazzer = "0.22.1"
 jcache = "1.1.1"
 jcommander = "1.82"
 jctools = "4.0.3"
@@ -67,7 +68,7 @@ kotlin = "1.9.23"
 lincheck = "2.27"
 mockito = "5.11.0"
 nexus-publish = "2.0.0-rc-2"
-nullaway-core = "0.10.24"
+nullaway-core = "0.10.25"
 nullaway-plugin = "2.0.0"
 okhttp-bom = "4.12.0"
 okio-bom = "3.9.0"
@@ -82,7 +83,7 @@ protobuf = "4.26.1"
 slf4j = "2.0.12"
 slf4j-test = "3.0.1"
 snakeyaml = "2.2"
-sonarqube = "4.4.1.3373"
+sonarqube = "5.0.0.4638"
 spotbugs-contrib = "7.6.4"
 spotbugs-core = "4.8.3"
 spotbugs-plugin = "6.0.9"
@@ -156,6 +157,7 @@ jakarta-inject = { module = "jakarta.inject:jakarta.inject-api", version.ref = "
 jamm = { module = "com.github.jbellis:jamm", version.ref = "jamm" }
 java-object-layout = { module = "org.openjdk.jol:jol-cli", version.ref = "java-object-layout" }
 javapoet = { module = "com.squareup:javapoet", version.ref = "javapoet" }
+jazzer = { module = "com.code-intelligence:jazzer-junit", version.ref = "jazzer" }
 jcache = { module = "javax.cache:cache-api", version.ref = "jcache" }
 jcache-guice = { module = "org.jsr107.ri:cache-annotations-ri-guice", version.ref = "jcache" }
 jcache-tck = { module = "javax.cache:cache-tests", version.ref = "jcache" }
diff --git a/gradle/plugins/src/main/kotlin/analyze/jmh-caffeine-conventions.gradle.kts b/gradle/plugins/src/main/kotlin/analyze/jmh-caffeine-conventions.gradle.kts
index b29a4940d7..7a094ae9b3 100644
--- a/gradle/plugins/src/main/kotlin/analyze/jmh-caffeine-conventions.gradle.kts
+++ b/gradle/plugins/src/main/kotlin/analyze/jmh-caffeine-conventions.gradle.kts
@@ -14,6 +14,7 @@ plugins {
 
 configurations.jmh {
   extendsFrom(configurations.testImplementation.get())
+  exclude(module = "jazzer-junit")
   exclude(module = "slf4j-test")
 }
 
diff --git a/jcache/src/main/java/com/github/benmanes/caffeine/jcache/CacheFactory.java b/jcache/src/main/java/com/github/benmanes/caffeine/jcache/CacheFactory.java
index b898dc57e6..5e484c2430 100644
--- a/jcache/src/main/java/com/github/benmanes/caffeine/jcache/CacheFactory.java
+++ b/jcache/src/main/java/com/github/benmanes/caffeine/jcache/CacheFactory.java
@@ -72,6 +72,7 @@ public static boolean isDefinedExternally(CacheManager cacheManager, String cach
    * @param cacheName the name of the cache
    * @return a new cache instance or null if the named cache is not defined in the settings file
    */
+  @SuppressWarnings("resource")
   public static @Nullable <K, V> CacheProxy<K, V> tryToCreateFromExternalSettings(
       CacheManager cacheManager, String cacheName) {
     return TypesafeConfigurator.<K, V>from(rootConfig(cacheManager), cacheName)
diff --git a/jcache/src/main/java/com/github/benmanes/caffeine/jcache/CacheProxy.java b/jcache/src/main/java/com/github/benmanes/caffeine/jcache/CacheProxy.java
index 3c7d231cd6..07c0241115 100644
--- a/jcache/src/main/java/com/github/benmanes/caffeine/jcache/CacheProxy.java
+++ b/jcache/src/main/java/com/github/benmanes/caffeine/jcache/CacheProxy.java
@@ -859,8 +859,7 @@ public <C extends Configuration<K, V>> C getConfiguration(Class<C> clazz) {
   }
 
   /** Returns the updated expirable value after performing the post-processing actions. */
-  @SuppressWarnings({"fallthrough", "NullAway",
-    "PMD.MissingBreakInSwitch", "PMD.SwitchStmtsShouldHaveDefault"})
+  @SuppressWarnings({"fallthrough", "NullAway", "PMD.MissingBreakInSwitch"})
   private @Nullable Expirable<V> postProcess(@Nullable Expirable<V> expirable,
       EntryProcessorEntry<K, V> entry, long currentTimeMS) {
     switch (entry.getAction()) {
diff --git a/jcache/src/main/java/com/github/benmanes/caffeine/jcache/event/EventDispatcher.java b/jcache/src/main/java/com/github/benmanes/caffeine/jcache/event/EventDispatcher.java
index 175d50e194..0059c37493 100644
--- a/jcache/src/main/java/com/github/benmanes/caffeine/jcache/event/EventDispatcher.java
+++ b/jcache/src/main/java/com/github/benmanes/caffeine/jcache/event/EventDispatcher.java
@@ -239,6 +239,7 @@ private void publish(Cache<K, V> cache, EventType eventType, K key,
       JCacheEntryEvent<K, V> e = event;
       var dispatchQueue = entry.getValue();
       var future = dispatchQueue.compute(key, (k, queue) -> {
+        @SuppressWarnings("resource")
         Runnable action = () -> registration.getCacheEntryListener().dispatch(e);
         return (queue == null)
             ? CompletableFuture.runAsync(action, executor)
diff --git a/jcache/src/main/java/com/github/benmanes/caffeine/jcache/event/EventTypeAwareListener.java b/jcache/src/main/java/com/github/benmanes/caffeine/jcache/event/EventTypeAwareListener.java
index ad184dd70b..36773a1440 100644
--- a/jcache/src/main/java/com/github/benmanes/caffeine/jcache/event/EventTypeAwareListener.java
+++ b/jcache/src/main/java/com/github/benmanes/caffeine/jcache/event/EventTypeAwareListener.java
@@ -47,7 +47,6 @@ public EventTypeAwareListener(CacheEntryListener<? super K, ? super V> listener)
   }
 
   /** Returns if the backing listener consumes this type of event. */
-  @SuppressWarnings("PMD.SwitchStmtsShouldHaveDefault")
   public boolean isCompatible(EventType eventType) {
     switch (eventType) {
       case CREATED:
@@ -63,7 +62,6 @@ public boolean isCompatible(EventType eventType) {
   }
 
   /** Processes the event and logs if an exception is thrown. */
-  @SuppressWarnings("PMD.SwitchStmtsShouldHaveDefault")
   public void dispatch(JCacheEntryEvent<K, V> event) {
     try {
       if (event.getSource().isClosed()) {
diff --git a/jcache/src/main/java/com/github/benmanes/caffeine/jcache/event/EventTypeFilter.java b/jcache/src/main/java/com/github/benmanes/caffeine/jcache/event/EventTypeFilter.java
index 5cdc055be5..c1a870dd5e 100644
--- a/jcache/src/main/java/com/github/benmanes/caffeine/jcache/event/EventTypeFilter.java
+++ b/jcache/src/main/java/com/github/benmanes/caffeine/jcache/event/EventTypeFilter.java
@@ -49,7 +49,6 @@ public boolean evaluate(CacheEntryEvent<? extends K, ? extends V> event) {
     return isCompatible(event) && filter.evaluate(event);
   }
 
-  @SuppressWarnings("PMD.SwitchStmtsShouldHaveDefault")
   private boolean isCompatible(CacheEntryEvent<? extends K, ? extends V> event) {
     switch (event.getEventType()) {
       case CREATED:
diff --git a/simulator/src/main/java/com/github/benmanes/caffeine/cache/simulator/policy/sketch/climbing/gradient/Stochastic.java b/simulator/src/main/java/com/github/benmanes/caffeine/cache/simulator/policy/sketch/climbing/gradient/Stochastic.java
index 9d835dce74..ea716eaec5 100644
--- a/simulator/src/main/java/com/github/benmanes/caffeine/cache/simulator/policy/sketch/climbing/gradient/Stochastic.java
+++ b/simulator/src/main/java/com/github/benmanes/caffeine/cache/simulator/policy/sketch/climbing/gradient/Stochastic.java
@@ -60,7 +60,6 @@ public Stochastic(Config config) {
   }
 
   @Override
-  @SuppressWarnings("PMD.SwitchStmtsShouldHaveDefault")
   protected double adjust(double hitRate) {
     double currentMissRate = (1 - hitRate);
     double previousMissRate = (1 - previousHitRate);
diff --git a/simulator/src/main/java/com/github/benmanes/caffeine/cache/simulator/policy/two_queue/TwoQueuePolicy.java b/simulator/src/main/java/com/github/benmanes/caffeine/cache/simulator/policy/two_queue/TwoQueuePolicy.java
index 88f9ccf2ee..eed3c14ae8 100644
--- a/simulator/src/main/java/com/github/benmanes/caffeine/cache/simulator/policy/two_queue/TwoQueuePolicy.java
+++ b/simulator/src/main/java/com/github/benmanes/caffeine/cache/simulator/policy/two_queue/TwoQueuePolicy.java
@@ -111,6 +111,7 @@ public void record(long key) {
           policyStats.recordHit();
           return;
       }
+      throw new IllegalStateException("Unknown type: " + node.type);
     } else {
       node = new Node(key);
       node.type = QueueType.IN;