diff --git a/briar-api/src/main/java/org/briarproject/briar/api/sharing/SharingManager.java b/briar-api/src/main/java/org/briarproject/briar/api/sharing/SharingManager.java
index 3e6adc2dc..2170744ed 100644
--- a/briar-api/src/main/java/org/briarproject/briar/api/sharing/SharingManager.java
+++ b/briar-api/src/main/java/org/briarproject/briar/api/sharing/SharingManager.java
@@ -3,6 +3,7 @@ package org.briarproject.briar.api.sharing;
 import org.briarproject.bramble.api.contact.Contact;
 import org.briarproject.bramble.api.contact.ContactId;
 import org.briarproject.bramble.api.db.DbException;
+import org.briarproject.bramble.api.db.Transaction;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 import org.briarproject.bramble.api.sync.GroupId;
 import org.briarproject.briar.api.client.SessionId;
@@ -45,6 +46,12 @@ public interface SharingManager<S extends Shareable>
 	 */
 	Collection<Contact> getSharedWith(GroupId g) throws DbException;
 
+	/**
+	 * Returns all contacts with whom the given group is shared.
+	 */
+	Collection<Contact> getSharedWith(Transaction txn, GroupId g)
+			throws DbException;
+
 	/**
 	 * Returns true if the group not already shared and no invitation is open
 	 */
diff --git a/briar-core/src/main/java/org/briarproject/briar/sharing/SharingManagerImpl.java b/briar-core/src/main/java/org/briarproject/briar/sharing/SharingManagerImpl.java
index 2b3abbd64..4a24ece90 100644
--- a/briar-core/src/main/java/org/briarproject/briar/sharing/SharingManagerImpl.java
+++ b/briar-core/src/main/java/org/briarproject/briar/sharing/SharingManagerImpl.java
@@ -426,17 +426,17 @@ abstract class SharingManagerImpl<S extends Shareable>
 
 	@Override
 	public Collection<Contact> getSharedWith(GroupId g) throws DbException {
+		return db.transactionWithResult(true, txn -> getSharedWith(txn, g));
+	}
+
+	@Override
+	public Collection<Contact> getSharedWith(Transaction txn, GroupId g)
+			throws DbException {
 		// TODO report also pending invitations
 		Collection<Contact> contacts = new ArrayList<>();
-		Transaction txn = db.startTransaction(true);
-		try {
-			for (Contact c : db.getContacts(txn)) {
-				if (db.getGroupVisibility(txn, c.getId(), g) == SHARED)
-					contacts.add(c);
-			}
-			db.commitTransaction(txn);
-		} finally {
-			db.endTransaction(txn);
+		for (Contact c : db.getContacts(txn)) {
+			if (db.getGroupVisibility(txn, c.getId(), g) == SHARED)
+				contacts.add(c);
 		}
 		return contacts;
 	}