diff --git a/bramble-core/src/main/java/org/briarproject/bramble/mailbox/MailboxModule.java b/bramble-core/src/main/java/org/briarproject/bramble/mailbox/MailboxModule.java
index 7fe5d0824..2141851ee 100644
--- a/bramble-core/src/main/java/org/briarproject/bramble/mailbox/MailboxModule.java
+++ b/bramble-core/src/main/java/org/briarproject/bramble/mailbox/MailboxModule.java
@@ -52,6 +52,7 @@ public class MailboxModule {
 	}
 
 	@Provides
+	@Singleton
 	MailboxSettingsManager provideMailboxSettingsManager(
 			MailboxSettingsManagerImpl mailboxSettingsManager) {
 		return mailboxSettingsManager;
diff --git a/bramble-core/src/main/java/org/briarproject/bramble/mailbox/MailboxSettingsManagerImpl.java b/bramble-core/src/main/java/org/briarproject/bramble/mailbox/MailboxSettingsManagerImpl.java
index 23f9ca486..3e285d930 100644
--- a/bramble-core/src/main/java/org/briarproject/bramble/mailbox/MailboxSettingsManagerImpl.java
+++ b/bramble-core/src/main/java/org/briarproject/bramble/mailbox/MailboxSettingsManagerImpl.java
@@ -20,13 +20,13 @@ import java.util.List;
 import java.util.concurrent.CopyOnWriteArrayList;
 
 import javax.annotation.Nullable;
-import javax.annotation.concurrent.Immutable;
+import javax.annotation.concurrent.ThreadSafe;
 import javax.inject.Inject;
 
 import static java.util.Collections.emptyList;
 import static org.briarproject.bramble.util.StringUtils.isNullOrEmpty;
 
-@Immutable
+@ThreadSafe
 @NotNullByDefault
 class MailboxSettingsManagerImpl implements MailboxSettingsManager {