diff --git a/bramble-core/src/main/java/org/briarproject/bramble/mailbox/ContactMailboxConnectivityChecker.java b/bramble-core/src/main/java/org/briarproject/bramble/mailbox/ContactMailboxConnectivityChecker.java
index 8759aa595..8922948c6 100644
--- a/bramble-core/src/main/java/org/briarproject/bramble/mailbox/ContactMailboxConnectivityChecker.java
+++ b/bramble-core/src/main/java/org/briarproject/bramble/mailbox/ContactMailboxConnectivityChecker.java
@@ -5,8 +5,6 @@ import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 import org.briarproject.bramble.api.system.Clock;
 import org.briarproject.bramble.mailbox.MailboxApi.ApiException;
 
-import java.io.IOException;
-
 import javax.annotation.concurrent.ThreadSafe;
 
 @ThreadSafe
@@ -24,16 +22,11 @@ class ContactMailboxConnectivityChecker extends ConnectivityCheckerImpl {
 	@Override
 	ApiCall createConnectivityCheckTask(MailboxProperties properties) {
 		if (properties.isOwner()) throw new IllegalArgumentException();
-		return new SimpleApiCall() {
-			@Override
-			void tryToCallApi() throws IOException, ApiException {
-				if (!mailboxApi.checkStatus(properties)) {
-					throw new ApiException();
-				}
-				// Call the observers and cache the result
-				onConnectivityCheckSucceeded(clock.currentTimeMillis());
-			}
-		};
+		return new SimpleApiCall(() -> {
+			if (!mailboxApi.checkStatus(properties)) throw new ApiException();
+			// Call the observers and cache the result
+			onConnectivityCheckSucceeded(clock.currentTimeMillis());
+		});
 	}
 
 }
diff --git a/bramble-core/src/main/java/org/briarproject/bramble/mailbox/SimpleApiCall.java b/bramble-core/src/main/java/org/briarproject/bramble/mailbox/SimpleApiCall.java
index 7c3e6f4b0..9a34a6244 100644
--- a/bramble-core/src/main/java/org/briarproject/bramble/mailbox/SimpleApiCall.java
+++ b/bramble-core/src/main/java/org/briarproject/bramble/mailbox/SimpleApiCall.java
@@ -16,17 +16,20 @@ import static org.briarproject.bramble.util.LogUtils.logException;
  * Convenience class for making simple API calls that don't return values.
  */
 @NotNullByDefault
-public abstract class SimpleApiCall implements ApiCall {
+class SimpleApiCall implements ApiCall {
 
 	private static final Logger LOG = getLogger(SimpleApiCall.class.getName());
 
-	abstract void tryToCallApi()
-			throws IOException, ApiException, TolerableFailureException;
+	private final Attempt attempt;
+
+	SimpleApiCall(Attempt attempt) {
+		this.attempt = attempt;
+	}
 
 	@Override
 	public boolean callApi() {
 		try {
-			tryToCallApi();
+			attempt.tryToCallApi();
 			return false; // Succeeded, don't retry
 		} catch (IOException | ApiException e) {
 			logException(LOG, WARNING, e);
@@ -36,4 +39,17 @@ public abstract class SimpleApiCall implements ApiCall {
 			return false; // Failed tolerably, don't retry
 		}
 	}
+
+	interface Attempt {
+
+		/**
+		 * Makes a single attempt to call an API endpoint. If this method
+		 * throws an {@link IOException} or an {@link ApiException}, the call
+		 * will be retried. If it throws a {@link TolerableFailureException}
+		 * or returns without throwing an exception, the call will not be
+		 * retried.
+		 */
+		void tryToCallApi()
+				throws IOException, ApiException, TolerableFailureException;
+	}
 }