diff --git a/bramble-core/src/main/java/org/briarproject/bramble/sync/validation/ValidationManagerImpl.java b/bramble-core/src/main/java/org/briarproject/bramble/sync/validation/ValidationManagerImpl.java
index cec81615d..ac22c3593 100644
--- a/bramble-core/src/main/java/org/briarproject/bramble/sync/validation/ValidationManagerImpl.java
+++ b/bramble-core/src/main/java/org/briarproject/bramble/sync/validation/ValidationManagerImpl.java
@@ -233,6 +233,9 @@ class ValidationManagerImpl implements ValidationManager, Service,
 		if (v == null) {
 			if (LOG.isLoggable(WARNING)) LOG.warning("No validator for " + cv);
 		} else {
+			if (LOG.isLoggable(INFO)) {
+				LOG.info("Validating message for " + cv.getClientId());
+			}
 			try {
 				MessageContext context = v.validateMessage(m, g);
 				storeMessageContextAsync(m, g.getClientId(),
@@ -323,6 +326,9 @@ class ValidationManagerImpl implements ValidationManager, Service,
 		ClientMajorVersion cv = new ClientMajorVersion(c, majorVersion);
 		IncomingMessageHook hook = hooks.get(cv);
 		if (hook == null) return ACCEPT_DO_NOT_SHARE;
+		if (LOG.isLoggable(INFO)) {
+			LOG.info("Delivering message for " + c);
+		}
 		try {
 			return hook.incomingMessage(txn, m, meta);
 		} catch (DbException e) {
diff --git a/bramble-core/src/test/java/org/briarproject/bramble/transport/agreement/TransportKeyAgreementIntegrationTest.java b/bramble-core/src/test/java/org/briarproject/bramble/transport/agreement/TransportKeyAgreementIntegrationTest.java
index 21bfb7df4..bd6d778aa 100644
--- a/bramble-core/src/test/java/org/briarproject/bramble/transport/agreement/TransportKeyAgreementIntegrationTest.java
+++ b/bramble-core/src/test/java/org/briarproject/bramble/transport/agreement/TransportKeyAgreementIntegrationTest.java
@@ -345,11 +345,16 @@ public class TransportKeyAgreementIntegrationTest
 					.canSendOutgoingStreams(aliceId, DUPLEX_TRANSPORT_ID));
 		}
 
-		// Sync initial client versioning updates and mailbox updates
+		// Sync client versioning update from Alice to Bob
 		syncMessage(alice, bob, bobId, 1, true);
+		// Sync client versioning update and ack from Bob to Alice
 		syncMessage(bob, alice, aliceId, 1, true);
+		// Sync second client versioning update, mailbox properties and ack
+		// from Alice to Bob
 		syncMessage(alice, bob, bobId, 2, true);
+		// Sync mailbox properties and ack from Bob to Alice
 		syncMessage(bob, alice, aliceId, 1, true);
+		// Sync final ack from Alice to Bob
 		sendAcks(alice, bob, bobId, 1);
 
 		return new Pair<>(aliceId, bobId);
diff --git a/briar-core/src/test/java/org/briarproject/briar/introduction/IntroductionIntegrationTest.java b/briar-core/src/test/java/org/briarproject/briar/introduction/IntroductionIntegrationTest.java
index 88e13b57a..dd980aa18 100644
--- a/briar-core/src/test/java/org/briarproject/briar/introduction/IntroductionIntegrationTest.java
+++ b/briar-core/src/test/java/org/briarproject/briar/introduction/IntroductionIntegrationTest.java
@@ -1057,6 +1057,7 @@ public class IntroductionIntegrationTest
 		sync1To0(1, true);
 		sync0To1(3, true);
 		sync1To0(2, true);
+		ack0To1(2);
 
 		// a new introduction should be possible
 		assertTrue(introductionManager0
diff --git a/briar-core/src/test/java/org/briarproject/briar/test/BriarIntegrationTest.java b/briar-core/src/test/java/org/briarproject/briar/test/BriarIntegrationTest.java
index 2dd294b79..71830e597 100644
--- a/briar-core/src/test/java/org/briarproject/briar/test/BriarIntegrationTest.java
+++ b/briar-core/src/test/java/org/briarproject/briar/test/BriarIntegrationTest.java
@@ -172,17 +172,28 @@ public abstract class BriarIntegrationTest<C extends BriarIntegrationTestCompone
 				true);
 		contact0From2 = contactManager2.getContact(contactId0From2);
 
-		// Sync initial client versioning updates and mailbox updates
+		// Sync client versioning update from 0 to 1
 		sync0To1(1, true);
+		// Sync client versioning update and ack from 1 to 0
 		sync1To0(1, true);
+		// Sync second client versioning update, mailbox properties and ack
+		// from 0 to 1
 		sync0To1(2, true);
+		// Sync mailbox properties and ack from 1 to 0
 		sync1To0(1, true);
+		// Sync final ack from 0 to 1
 		ack0To1(1);
 
+		// Sync client versioning update from 0 to 2
 		sync0To2(1, true);
+		// Sync client versioning update and ack from 2 to 0
 		sync2To0(1, true);
+		// Sync second client versioning update, mailbox properties and ack
+		// from 0 to 2
 		sync0To2(2, true);
+		// Sync mailbox properties and ack from 2 to 0
 		sync2To0(1, true);
+		// Sync final ack from 0 to 2
 		ack0To2(1);
 	}
 
@@ -199,18 +210,26 @@ public abstract class BriarIntegrationTest<C extends BriarIntegrationTestCompone
 				rootKey1_2, c2.getClock().currentTimeMillis(), false, true,
 				true);
 
-		// Sync initial client versioning updates
+		// Sync initial client versioning update from 1 to 2
 		sync1To2(1, true);
+		// Sync initial client versioning update and ack from 2 to 1
 		sync2To1(1, true);
-		// Sync 2nd client versioning msg from 1to2, mailbox updates, and
-		// transport properties if we should
 		if (haveTransportProperties) {
+			// Sync second client versioning update, mailbox properties,
+			// transport properties and ack from 1 to 2
 			sync1To2(3, true);
+			// Sync mailbox properties, transport properties and acks
+			// from 2 to 1
 			sync2To1(2, true);
+			// Sync final acks from 1 to 2
 			ack1To2(2);
 		} else {
+			// Sync second client versioning update, mailbox properties
+			// and ack from 1 to 2
 			sync1To2(2, true);
+			// Sync mailbox properties and acks from 2 to 1
 			sync2To1(1, true);
+			// Sync final ack from 1 to 2
 			ack1To2(1);
 		}
 	}