diff --git a/android/guava-tests/test/com/google/common/base/EnumsTest.java b/android/guava-tests/test/com/google/common/base/EnumsTest.java
index 8560265d3418..394bbd3689b2 100644
--- a/android/guava-tests/test/com/google/common/base/EnumsTest.java
+++ b/android/guava-tests/test/com/google/common/base/EnumsTest.java
@@ -83,6 +83,7 @@ public void testGetIfPresent_whenNoMatchingConstant() {
 
 
   @J2ktIncompatible
+  @GwtIncompatible // weak references
   @AndroidIncompatible // depends on details of GC and classloading
   public void testGetIfPresent_doesNotPreventClassUnloading() throws Exception {
     WeakReference<?> shadowLoaderReference = doTestClassUnloading();
@@ -95,6 +96,7 @@ public void testGetIfPresent_doesNotPreventClassUnloading() throws Exception {
   // (and therefore its ClassLoader) from being unloaded, then this WeakReference will never be
   // cleared.
   @J2ktIncompatible
+  @GwtIncompatible // weak references
   private WeakReference<?> doTestClassUnloading() throws Exception {
     URLClassLoader shadowLoader = new URLClassLoader(getClassPathUrls(), null);
     @SuppressWarnings("unchecked")
@@ -115,6 +117,7 @@ private WeakReference<?> doTestClassUnloading() throws Exception {
     return new WeakReference<>(shadowLoader);
   }
 
+  @GwtIncompatible // stringConverter
   public void testStringConverter_convert() {
     Converter<String, TestEnum> converter = Enums.stringConverter(TestEnum.class);
     assertEquals(TestEnum.CHEETO, converter.convert("CHEETO"));
@@ -124,11 +127,13 @@ public void testStringConverter_convert() {
     assertNull(converter.reverse().convert(null));
   }
 
+  @GwtIncompatible // stringConverter
   public void testStringConverter_convertError() {
     Converter<String, TestEnum> converter = Enums.stringConverter(TestEnum.class);
     assertThrows(IllegalArgumentException.class, () -> converter.convert("xxx"));
   }
 
+  @GwtIncompatible // stringConverter
   public void testStringConverter_reverse() {
     Converter<String, TestEnum> converter = Enums.stringConverter(TestEnum.class);
     assertEquals("CHEETO", converter.reverse().convert(TestEnum.CHEETO));
@@ -137,12 +142,14 @@ public void testStringConverter_reverse() {
   }
 
   @J2ktIncompatible
+  @GwtIncompatible // stringConverter
   public void testStringConverter_nullPointerTester() throws Exception {
     Converter<String, TestEnum> converter = Enums.stringConverter(TestEnum.class);
     NullPointerTester tester = new NullPointerTester();
     tester.testAllPublicInstanceMethods(converter);
   }
 
+  @GwtIncompatible // stringConverter
   public void testStringConverter_nullConversions() {
     Converter<String, TestEnum> converter = Enums.stringConverter(TestEnum.class);
     assertNull(converter.convert(null));
@@ -150,17 +157,20 @@ public void testStringConverter_nullConversions() {
   }
 
   @J2ktIncompatible
+  @GwtIncompatible // Class.getName()
   public void testStringConverter_toString() {
     assertEquals(
         "Enums.stringConverter(com.google.common.base.EnumsTest$TestEnum.class)",
         Enums.stringConverter(TestEnum.class).toString());
   }
 
+  @GwtIncompatible // stringConverter
   public void testStringConverter_serialization() {
     SerializableTester.reserializeAndAssert(Enums.stringConverter(TestEnum.class));
   }
 
   @J2ktIncompatible
+  @GwtIncompatible // NullPointerTester
   public void testNullPointerExceptions() {
     NullPointerTester tester = new NullPointerTester();
     tester.testAllPublicStaticMethods(Enums.class);
@@ -176,6 +186,7 @@ private enum AnEnum {
   }
 
   @J2ktIncompatible
+  @GwtIncompatible // reflection
   public void testGetField() {
     Field foo = Enums.getField(AnEnum.FOO);
     assertEquals("FOO", foo.getName());
@@ -187,6 +198,7 @@ public void testGetField() {
   }
 
   @J2ktIncompatible
+  @GwtIncompatible // Class.getClassLoader()
   private URL[] getClassPathUrls() {
     ClassLoader classLoader = getClass().getClassLoader();
     return classLoader instanceof URLClassLoader
@@ -200,6 +212,7 @@ private URL[] getClassPathUrls() {
    */
   // TODO(b/65488446): Make this a public API.
   @J2ktIncompatible
+  @GwtIncompatible
   private static ImmutableList<URL> parseJavaClassPath() {
     ImmutableList.Builder<URL> urls = ImmutableList.builder();
     for (String entry : Splitter.on(PATH_SEPARATOR.value()).split(JAVA_CLASS_PATH.value())) {
diff --git a/android/guava/src/com/google/common/base/Enums.java b/android/guava/src/com/google/common/base/Enums.java
index 5587cbf9627d..d39103b0c7ed 100644
--- a/android/guava/src/com/google/common/base/Enums.java
+++ b/android/guava/src/com/google/common/base/Enums.java
@@ -46,6 +46,7 @@ private Enums() {}
    *
    * @since 12.0
    */
+  @GwtIncompatible // reflection
   public static Field getField(Enum<?> enumValue) {
     Class<?>
         clazz = enumValue.getDeclaringClass();
@@ -70,9 +71,11 @@ public static <T extends Enum<T>> Optional<T> getIfPresent(Class<T> enumClass, S
     return Platform.getEnumIfPresent(enumClass, value);
   }
 
+  @GwtIncompatible // java.lang.ref.WeakReference
   private static final Map<Class<? extends Enum<?>>, Map<String, WeakReference<? extends Enum<?>>>>
       enumConstantCache = new WeakHashMap<>();
 
+  @GwtIncompatible // java.lang.ref.WeakReference
   private static <T extends Enum<T>> Map<String, WeakReference<? extends Enum<?>>> populateCache(
       Class<T> enumClass) {
     Map<String, WeakReference<? extends Enum<?>>> result = new HashMap<>();
@@ -83,6 +86,7 @@ private static <T extends Enum<T>> Map<String, WeakReference<? extends Enum<?>>>
     return result;
   }
 
+  @GwtIncompatible // java.lang.ref.WeakReference
   static <T extends Enum<T>> Map<String, WeakReference<? extends Enum<?>>> getEnumConstants(
       Class<T> enumClass) {
     synchronized (enumConstantCache) {
@@ -102,10 +106,12 @@ static <T extends Enum<T>> Map<String, WeakReference<? extends Enum<?>>> getEnum
    *
    * @since 16.0
    */
+  @GwtIncompatible
   public static <T extends Enum<T>> Converter<String, T> stringConverter(Class<T> enumClass) {
     return new StringConverter<>(enumClass);
   }
 
+  @GwtIncompatible
   private static final class StringConverter<T extends Enum<T>> extends Converter<String, T>
       implements Serializable {
 
@@ -144,6 +150,6 @@ public String toString() {
       return "Enums.stringConverter(" + enumClass.getName() + ".class)";
     }
 
-    @J2ktIncompatible private static final long serialVersionUID = 0L;
+    @GwtIncompatible @J2ktIncompatible private static final long serialVersionUID = 0L;
   }
 }
diff --git a/guava-tests/test/com/google/common/base/EnumsTest.java b/guava-tests/test/com/google/common/base/EnumsTest.java
index 8560265d3418..394bbd3689b2 100644
--- a/guava-tests/test/com/google/common/base/EnumsTest.java
+++ b/guava-tests/test/com/google/common/base/EnumsTest.java
@@ -83,6 +83,7 @@ public void testGetIfPresent_whenNoMatchingConstant() {
 
 
   @J2ktIncompatible
+  @GwtIncompatible // weak references
   @AndroidIncompatible // depends on details of GC and classloading
   public void testGetIfPresent_doesNotPreventClassUnloading() throws Exception {
     WeakReference<?> shadowLoaderReference = doTestClassUnloading();
@@ -95,6 +96,7 @@ public void testGetIfPresent_doesNotPreventClassUnloading() throws Exception {
   // (and therefore its ClassLoader) from being unloaded, then this WeakReference will never be
   // cleared.
   @J2ktIncompatible
+  @GwtIncompatible // weak references
   private WeakReference<?> doTestClassUnloading() throws Exception {
     URLClassLoader shadowLoader = new URLClassLoader(getClassPathUrls(), null);
     @SuppressWarnings("unchecked")
@@ -115,6 +117,7 @@ private WeakReference<?> doTestClassUnloading() throws Exception {
     return new WeakReference<>(shadowLoader);
   }
 
+  @GwtIncompatible // stringConverter
   public void testStringConverter_convert() {
     Converter<String, TestEnum> converter = Enums.stringConverter(TestEnum.class);
     assertEquals(TestEnum.CHEETO, converter.convert("CHEETO"));
@@ -124,11 +127,13 @@ public void testStringConverter_convert() {
     assertNull(converter.reverse().convert(null));
   }
 
+  @GwtIncompatible // stringConverter
   public void testStringConverter_convertError() {
     Converter<String, TestEnum> converter = Enums.stringConverter(TestEnum.class);
     assertThrows(IllegalArgumentException.class, () -> converter.convert("xxx"));
   }
 
+  @GwtIncompatible // stringConverter
   public void testStringConverter_reverse() {
     Converter<String, TestEnum> converter = Enums.stringConverter(TestEnum.class);
     assertEquals("CHEETO", converter.reverse().convert(TestEnum.CHEETO));
@@ -137,12 +142,14 @@ public void testStringConverter_reverse() {
   }
 
   @J2ktIncompatible
+  @GwtIncompatible // stringConverter
   public void testStringConverter_nullPointerTester() throws Exception {
     Converter<String, TestEnum> converter = Enums.stringConverter(TestEnum.class);
     NullPointerTester tester = new NullPointerTester();
     tester.testAllPublicInstanceMethods(converter);
   }
 
+  @GwtIncompatible // stringConverter
   public void testStringConverter_nullConversions() {
     Converter<String, TestEnum> converter = Enums.stringConverter(TestEnum.class);
     assertNull(converter.convert(null));
@@ -150,17 +157,20 @@ public void testStringConverter_nullConversions() {
   }
 
   @J2ktIncompatible
+  @GwtIncompatible // Class.getName()
   public void testStringConverter_toString() {
     assertEquals(
         "Enums.stringConverter(com.google.common.base.EnumsTest$TestEnum.class)",
         Enums.stringConverter(TestEnum.class).toString());
   }
 
+  @GwtIncompatible // stringConverter
   public void testStringConverter_serialization() {
     SerializableTester.reserializeAndAssert(Enums.stringConverter(TestEnum.class));
   }
 
   @J2ktIncompatible
+  @GwtIncompatible // NullPointerTester
   public void testNullPointerExceptions() {
     NullPointerTester tester = new NullPointerTester();
     tester.testAllPublicStaticMethods(Enums.class);
@@ -176,6 +186,7 @@ private enum AnEnum {
   }
 
   @J2ktIncompatible
+  @GwtIncompatible // reflection
   public void testGetField() {
     Field foo = Enums.getField(AnEnum.FOO);
     assertEquals("FOO", foo.getName());
@@ -187,6 +198,7 @@ public void testGetField() {
   }
 
   @J2ktIncompatible
+  @GwtIncompatible // Class.getClassLoader()
   private URL[] getClassPathUrls() {
     ClassLoader classLoader = getClass().getClassLoader();
     return classLoader instanceof URLClassLoader
@@ -200,6 +212,7 @@ private URL[] getClassPathUrls() {
    */
   // TODO(b/65488446): Make this a public API.
   @J2ktIncompatible
+  @GwtIncompatible
   private static ImmutableList<URL> parseJavaClassPath() {
     ImmutableList.Builder<URL> urls = ImmutableList.builder();
     for (String entry : Splitter.on(PATH_SEPARATOR.value()).split(JAVA_CLASS_PATH.value())) {
diff --git a/guava/src/com/google/common/base/Enums.java b/guava/src/com/google/common/base/Enums.java
index 5587cbf9627d..d39103b0c7ed 100644
--- a/guava/src/com/google/common/base/Enums.java
+++ b/guava/src/com/google/common/base/Enums.java
@@ -46,6 +46,7 @@ private Enums() {}
    *
    * @since 12.0
    */
+  @GwtIncompatible // reflection
   public static Field getField(Enum<?> enumValue) {
     Class<?>
         clazz = enumValue.getDeclaringClass();
@@ -70,9 +71,11 @@ public static <T extends Enum<T>> Optional<T> getIfPresent(Class<T> enumClass, S
     return Platform.getEnumIfPresent(enumClass, value);
   }
 
+  @GwtIncompatible // java.lang.ref.WeakReference
   private static final Map<Class<? extends Enum<?>>, Map<String, WeakReference<? extends Enum<?>>>>
       enumConstantCache = new WeakHashMap<>();
 
+  @GwtIncompatible // java.lang.ref.WeakReference
   private static <T extends Enum<T>> Map<String, WeakReference<? extends Enum<?>>> populateCache(
       Class<T> enumClass) {
     Map<String, WeakReference<? extends Enum<?>>> result = new HashMap<>();
@@ -83,6 +86,7 @@ private static <T extends Enum<T>> Map<String, WeakReference<? extends Enum<?>>>
     return result;
   }
 
+  @GwtIncompatible // java.lang.ref.WeakReference
   static <T extends Enum<T>> Map<String, WeakReference<? extends Enum<?>>> getEnumConstants(
       Class<T> enumClass) {
     synchronized (enumConstantCache) {
@@ -102,10 +106,12 @@ static <T extends Enum<T>> Map<String, WeakReference<? extends Enum<?>>> getEnum
    *
    * @since 16.0
    */
+  @GwtIncompatible
   public static <T extends Enum<T>> Converter<String, T> stringConverter(Class<T> enumClass) {
     return new StringConverter<>(enumClass);
   }
 
+  @GwtIncompatible
   private static final class StringConverter<T extends Enum<T>> extends Converter<String, T>
       implements Serializable {
 
@@ -144,6 +150,6 @@ public String toString() {
       return "Enums.stringConverter(" + enumClass.getName() + ".class)";
     }
 
-    @J2ktIncompatible private static final long serialVersionUID = 0L;
+    @GwtIncompatible @J2ktIncompatible private static final long serialVersionUID = 0L;
   }
 }