diff --git a/core/src/test/java/org/bitcoinj/core/Base58Test.java b/core/src/test/java/org/bitcoinj/core/Base58Test.java
index c6642bf1..b5340938 100644
--- a/core/src/test/java/org/bitcoinj/core/Base58Test.java
+++ b/core/src/test/java/org/bitcoinj/core/Base58Test.java
@@ -1,5 +1,6 @@
 /*
  * Copyright 2011 Google Inc.
+ * Copyright 2018 Andreas Schildbach
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -16,13 +17,16 @@
 
 package org.bitcoinj.core;
 
-import junit.framework.TestCase;
-import org.junit.Test;
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertTrue;
+import static org.junit.Assert.fail;
 
 import java.math.BigInteger;
 import java.util.Arrays;
 
-public class Base58Test extends TestCase {
+import org.junit.Test;
+
+public class Base58Test {
     @Test
     public void testEncode() throws Exception {
         byte[] testbytes = "Hello World".getBytes();
diff --git a/core/src/test/java/org/bitcoinj/core/VarIntTest.java b/core/src/test/java/org/bitcoinj/core/VarIntTest.java
index 8c4e91e7..6592f900 100644
--- a/core/src/test/java/org/bitcoinj/core/VarIntTest.java
+++ b/core/src/test/java/org/bitcoinj/core/VarIntTest.java
@@ -1,5 +1,6 @@
 /*
  * Copyright 2011 Google Inc.
+ * Copyright 2018 Andreas Schildbach
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -16,11 +17,11 @@
 
 package org.bitcoinj.core;
 
-import junit.framework.TestCase;
+import static org.junit.Assert.assertEquals;
 
 import org.junit.Test;
 
-public class VarIntTest extends TestCase {
+public class VarIntTest {
 
     @Test
     public void testBytes() throws Exception {
diff --git a/core/src/test/java/org/bitcoinj/protocols/channels/PaymentChannelServerTest.java b/core/src/test/java/org/bitcoinj/protocols/channels/PaymentChannelServerTest.java
index 71640530..a9eced9b 100644
--- a/core/src/test/java/org/bitcoinj/protocols/channels/PaymentChannelServerTest.java
+++ b/core/src/test/java/org/bitcoinj/protocols/channels/PaymentChannelServerTest.java
@@ -30,11 +30,11 @@ import org.junit.runners.Parameterized;
 import java.util.Arrays;
 import java.util.Collection;
 
-import static junit.framework.TestCase.assertTrue;
 import static org.bitcoin.paymentchannel.Protos.TwoWayChannelMessage;
 import static org.bitcoin.paymentchannel.Protos.TwoWayChannelMessage.MessageType;
 import static org.easymock.EasyMock.*;
 import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertTrue;
 
 @RunWith(Parameterized.class)
 public class PaymentChannelServerTest {