diff --git a/proto/pom.xml b/proto/pom.xml
index 3ce08bbe..14fd44ce 100644
--- a/proto/pom.xml
+++ b/proto/pom.xml
@@ -55,35 +55,35 @@
     <dependency>
       <groupId>com.google.code.gson</groupId>
       <artifactId>gson</artifactId>
-      <version>2.4</version>
+      <version>2.8.8</version>
       <scope>compile</scope>
     </dependency>
 
     <dependency>
       <groupId>com.google.protobuf</groupId>
       <artifactId>protobuf-java</artifactId>
-      <version>2.6.1</version>
+      <version>4.0.0-rc-2</version>
       <scope>compile</scope>
     </dependency>
     
     <dependency>
       <groupId>com.google.guava</groupId>
       <artifactId>guava</artifactId>
-      <version>18.0</version>
+      <version>30.1.1-jre</version>
       <scope>compile</scope>
     </dependency>
 
     <dependency>
       <groupId>junit</groupId>
       <artifactId>junit</artifactId>
-      <version>4.13.1</version>
+      <version>4.13.2</version>
       <scope>test</scope>
     </dependency>
     
     <dependency>
       <groupId>com.google.truth</groupId>
       <artifactId>truth</artifactId>
-      <version>0.27</version>
+      <version>1.1.3</version>
       <scope>test</scope>
     </dependency>
   </dependencies>
diff --git a/proto/src/test/java/com/google/gson/protobuf/functional/ProtosWithAnnotationsTest.java b/proto/src/test/java/com/google/gson/protobuf/functional/ProtosWithAnnotationsTest.java
index 2bb6f183..0a508f9d 100644
--- a/proto/src/test/java/com/google/gson/protobuf/functional/ProtosWithAnnotationsTest.java
+++ b/proto/src/test/java/com/google/gson/protobuf/functional/ProtosWithAnnotationsTest.java
@@ -16,7 +16,7 @@
 package com.google.gson.protobuf.functional;
 
 import static com.google.common.truth.Truth.assertThat;
-import static com.google.common.truth.Truth.assert_;
+import static com.google.common.truth.Truth.assertWithMessage;
 
 import com.google.common.base.CaseFormat;
 import com.google.gson.Gson;
@@ -30,8 +30,7 @@ import com.google.gson.protobuf.generated.Bag.ProtoWithAnnotations;
 import com.google.gson.protobuf.generated.Bag.ProtoWithAnnotations.InnerMessage;
 import com.google.gson.protobuf.generated.Bag.ProtoWithAnnotations.InnerMessage.Data;
 import com.google.gson.protobuf.generated.Bag.ProtoWithAnnotations.InnerMessage.Type;
-import com.google.protobuf.GeneratedMessage;
-
+import com.google.protobuf.GeneratedMessageV3;
 import junit.framework.TestCase;
 
 /**
@@ -52,15 +51,15 @@ public class ProtosWithAnnotationsTest extends TestCase {
         .addSerializedNameExtension(Annotations.serializedName)
         .addSerializedEnumValueExtension(Annotations.serializedValue);
     gson = new GsonBuilder()
-        .registerTypeHierarchyAdapter(GeneratedMessage.class, protoTypeAdapter.build())
+        .registerTypeHierarchyAdapter(GeneratedMessageV3.class, protoTypeAdapter.build())
         .create();
     gsonWithEnumNumbers = new GsonBuilder()
-        .registerTypeHierarchyAdapter(GeneratedMessage.class, protoTypeAdapter
+        .registerTypeHierarchyAdapter(GeneratedMessageV3.class, protoTypeAdapter
             .setEnumSerialization(EnumSerialization.NUMBER)
             .build())
         .create();
     gsonWithLowerHyphen = new GsonBuilder()
-        .registerTypeHierarchyAdapter(GeneratedMessage.class, protoTypeAdapter
+        .registerTypeHierarchyAdapter(GeneratedMessageV3.class, protoTypeAdapter
             .setFieldNameSerializationFormat(CaseFormat.LOWER_UNDERSCORE, CaseFormat.LOWER_HYPHEN)
             .build())
         .create();
@@ -157,7 +156,7 @@ public class ProtosWithAnnotationsTest extends TestCase {
         + "}");
     try {
       gson.fromJson(json, InnerMessage.class);
-      assert_().fail("Should have thrown");
+      assertWithMessage("Should have thrown").fail();
     } catch (JsonParseException e) {
       // expected
     }
diff --git a/proto/src/test/java/com/google/gson/protobuf/functional/ProtosWithComplexAndRepeatedFieldsTest.java b/proto/src/test/java/com/google/gson/protobuf/functional/ProtosWithComplexAndRepeatedFieldsTest.java
index b61d3f50..8e59d5d1 100644
--- a/proto/src/test/java/com/google/gson/protobuf/functional/ProtosWithComplexAndRepeatedFieldsTest.java
+++ b/proto/src/test/java/com/google/gson/protobuf/functional/ProtosWithComplexAndRepeatedFieldsTest.java
@@ -24,8 +24,7 @@ import com.google.gson.protobuf.ProtoTypeAdapter.EnumSerialization;
 import com.google.gson.protobuf.generated.Bag.ProtoWithDifferentCaseFormat;
 import com.google.gson.protobuf.generated.Bag.ProtoWithRepeatedFields;
 import com.google.gson.protobuf.generated.Bag.SimpleProto;
-import com.google.protobuf.GeneratedMessage;
-
+import com.google.protobuf.GeneratedMessageV3;
 import junit.framework.TestCase;
 
 /**
@@ -42,7 +41,7 @@ public class ProtosWithComplexAndRepeatedFieldsTest extends TestCase {
     super.setUp();
     gson =
         new GsonBuilder()
-            .registerTypeHierarchyAdapter(GeneratedMessage.class,
+            .registerTypeHierarchyAdapter(GeneratedMessageV3.class,
                 ProtoTypeAdapter.newBuilder()
                     .setEnumSerialization(EnumSerialization.NUMBER)
                     .build())
@@ -50,7 +49,7 @@ public class ProtosWithComplexAndRepeatedFieldsTest extends TestCase {
     upperCamelGson =
         new GsonBuilder()
             .registerTypeHierarchyAdapter(
-                GeneratedMessage.class, ProtoTypeAdapter.newBuilder()
+                GeneratedMessageV3.class, ProtoTypeAdapter.newBuilder()
                     .setFieldNameSerializationFormat(
                         CaseFormat.LOWER_UNDERSCORE, CaseFormat.UPPER_CAMEL)
                     .build())
diff --git a/proto/src/test/java/com/google/gson/protobuf/functional/ProtosWithPrimitiveTypesTest.java b/proto/src/test/java/com/google/gson/protobuf/functional/ProtosWithPrimitiveTypesTest.java
index 69b877e6..2e9d0e17 100644
--- a/proto/src/test/java/com/google/gson/protobuf/functional/ProtosWithPrimitiveTypesTest.java
+++ b/proto/src/test/java/com/google/gson/protobuf/functional/ProtosWithPrimitiveTypesTest.java
@@ -21,8 +21,7 @@ import com.google.gson.protobuf.ProtoTypeAdapter;
 import com.google.gson.protobuf.ProtoTypeAdapter.EnumSerialization;
 import com.google.gson.protobuf.generated.Bag.SimpleProto;
 import com.google.protobuf.Descriptors.Descriptor;
-import com.google.protobuf.GeneratedMessage;
-
+import com.google.protobuf.GeneratedMessageV3;
 import junit.framework.TestCase;
 
 public class ProtosWithPrimitiveTypesTest extends TestCase {
@@ -32,7 +31,7 @@ public class ProtosWithPrimitiveTypesTest extends TestCase {
   protected void setUp() throws Exception {
     super.setUp();
     gson = new GsonBuilder().registerTypeHierarchyAdapter(
-      GeneratedMessage.class, ProtoTypeAdapter.newBuilder()
+      GeneratedMessageV3.class, ProtoTypeAdapter.newBuilder()
           .setEnumSerialization(EnumSerialization.NUMBER)
           .build())
       .create();