diff --git a/core/src/test/java/com/google/bitcoin/core/ECKeyTest.java b/core/src/test/java/com/google/bitcoin/core/ECKeyTest.java
index 99f9fd61..c8edd189 100644
--- a/core/src/test/java/com/google/bitcoin/core/ECKeyTest.java
+++ b/core/src/test/java/com/google/bitcoin/core/ECKeyTest.java
@@ -254,7 +254,7 @@ public class ECKeyTest {
 
     @Test
     public void testUnencryptedCreate() throws Exception {
-        Utils.rollMockClock(0);
+        Utils.setMockClock();
         ECKey key = new ECKey();
         long time = key.getCreationTimeSeconds();
         assertNotEquals(0, time);
diff --git a/core/src/test/java/com/google/bitcoin/core/FullBlockTestGenerator.java b/core/src/test/java/com/google/bitcoin/core/FullBlockTestGenerator.java
index 44e0adc5..7c025373 100644
--- a/core/src/test/java/com/google/bitcoin/core/FullBlockTestGenerator.java
+++ b/core/src/test/java/com/google/bitcoin/core/FullBlockTestGenerator.java
@@ -96,7 +96,7 @@ public class FullBlockTestGenerator {
         this.params = params;
         coinbaseOutKey = new ECKey();
         coinbaseOutKeyPubKey = coinbaseOutKey.getPubKey();
-        Utils.rollMockClock(0); // Set a mock clock for timestamp tests
+        Utils.setMockClock();
     }
 
     public RuleList getBlocksToTest(boolean addSigExpensiveBlocks, boolean runLargeReorgs, File blockStorageFile) throws ScriptException, ProtocolException, IOException {
diff --git a/core/src/test/java/com/google/bitcoin/core/PeerTest.java b/core/src/test/java/com/google/bitcoin/core/PeerTest.java
index d8d93b13..5caa15d9 100644
--- a/core/src/test/java/com/google/bitcoin/core/PeerTest.java
+++ b/core/src/test/java/com/google/bitcoin/core/PeerTest.java
@@ -36,7 +36,6 @@ import java.math.BigInteger;
 import java.net.InetSocketAddress;
 import java.net.SocketException;
 import java.nio.channels.CancelledKeyException;
-import java.nio.channels.ClosedChannelException;
 import java.nio.charset.Charset;
 import java.util.ArrayList;
 import java.util.Arrays;
@@ -436,7 +435,7 @@ public class PeerTest extends TestWithNetworkConnections {
     @Test
     public void fastCatchup() throws Exception {
         connect();
-        
+        Utils.setMockClock();
         // Check that blocks before the fast catchup point are retrieved using getheaders, and after using getblocks.
         // This test is INCOMPLETE because it does not check we handle >2000 blocks correctly.
         Block b1 = createFakeBlock(blockStore).block;
@@ -484,7 +483,7 @@ public class PeerTest extends TestWithNetworkConnections {
     @Test
     public void pingPong() throws Exception {
         connect();
-        Utils.rollMockClock(0);
+        Utils.setMockClock();
         // No ping pong happened yet.
         assertEquals(Long.MAX_VALUE, peer.getLastPingTime());
         assertEquals(Long.MAX_VALUE, peer.getPingTime());
diff --git a/core/src/test/java/com/google/bitcoin/core/WalletTest.java b/core/src/test/java/com/google/bitcoin/core/WalletTest.java
index 2bea4cc7..ac276e7c 100644
--- a/core/src/test/java/com/google/bitcoin/core/WalletTest.java
+++ b/core/src/test/java/com/google/bitcoin/core/WalletTest.java
@@ -948,7 +948,7 @@ public class WalletTest extends TestWithWallet {
     @Test
     public void transactionsList() throws Exception {
         // Check the wallet can give us an ordered list of all received transactions.
-        Utils.rollMockClock(0);
+        Utils.setMockClock();
         Transaction tx1 = sendMoneyToWallet(Utils.toNanoCoins(1, 0), AbstractBlockChain.NewBlockType.BEST_CHAIN);
         Utils.rollMockClock(60 * 10);
         Transaction tx2 = sendMoneyToWallet(Utils.toNanoCoins(0, 5), AbstractBlockChain.NewBlockType.BEST_CHAIN);
@@ -986,7 +986,8 @@ public class WalletTest extends TestWithWallet {
     @Test
     public void keyCreationTime() throws Exception {
         wallet = new Wallet(params);
-        long now = Utils.rollMockClock(0).getTime() / 1000;  // Fix the mock clock.
+        Utils.setMockClock();
+        long now = Utils.currentTimeSeconds();
         // No keys returns current time.
         assertEquals(now, wallet.getEarliestKeyCreationTime());
         Utils.rollMockClock(60);
@@ -1000,7 +1001,8 @@ public class WalletTest extends TestWithWallet {
     @Test
     public void scriptCreationTime() throws Exception {
         wallet = new Wallet(params);
-        long now = Utils.rollMockClock(0).getTime() / 1000;  // Fix the mock clock.
+        Utils.setMockClock();
+        long now = Utils.currentTimeSeconds();
         // No keys returns current time.
         assertEquals(now, wallet.getEarliestKeyCreationTime());
         Utils.rollMockClock(60);
@@ -2186,6 +2188,7 @@ public class WalletTest extends TestWithWallet {
 
     @Test
     public void keyRotation() throws Exception {
+        Utils.setMockClock();
         // Watch out for wallet-initiated broadcasts.
         MockTransactionBroadcaster broadcaster = new MockTransactionBroadcaster(wallet);
         wallet.setTransactionBroadcaster(broadcaster);
@@ -2258,6 +2261,7 @@ public class WalletTest extends TestWithWallet {
         ECKey key = new ECKey();
         wallet.addKey(key);
         Address address = key.toAddress(params);
+        Utils.setMockClock();
         Utils.rollMockClock(86400);
         for (int i = 0; i < 800; i++) {
             sendMoneyToWallet(wallet, Utils.CENT, address, AbstractBlockChain.NewBlockType.BEST_CHAIN);
diff --git a/core/src/test/java/com/google/bitcoin/protocols/channels/ChannelConnectionTest.java b/core/src/test/java/com/google/bitcoin/protocols/channels/ChannelConnectionTest.java
index e0ed05ca..0bd9b863 100644
--- a/core/src/test/java/com/google/bitcoin/protocols/channels/ChannelConnectionTest.java
+++ b/core/src/test/java/com/google/bitcoin/protocols/channels/ChannelConnectionTest.java
@@ -268,7 +268,7 @@ public class ChannelConnectionTest extends TestWithWallet {
     @Test
     public void testChannelResume() throws Exception {
         // Tests various aspects of channel resuming.
-        Utils.rollMockClock(0);
+        Utils.setMockClock();
 
         final Sha256Hash someServerId = Sha256Hash.create(new byte[]{});