diff --git a/MailKit/Net/Imap/ImapFolder.cs b/MailKit/Net/Imap/ImapFolder.cs
index b1ccaa1baf..0acca90c75 100644
--- a/MailKit/Net/Imap/ImapFolder.cs
+++ b/MailKit/Net/Imap/ImapFolder.cs
@@ -4508,7 +4508,7 @@ async Task<IList<int>> GetIndexesAsync (IList<UniqueId> uids, bool doAsync, Canc
 		{
 			var command = string.Format ("SEARCH UID {0}\r\n", UniqueIdSet.ToString (uids));
 			var ic = new ImapCommand (Engine, cancellationToken, this, command);
-			var results = new SearchResults ();
+			var results = new SearchResults (SortOrder.Ascending);
 
 			if ((Engine.Capabilities & ImapCapabilities.ESearch) != 0)
 				ic.RegisterUntaggedHandler ("ESEARCH", ESearchMatchesAsync);
diff --git a/MailKit/Net/Imap/ImapFolderSearch.cs b/MailKit/Net/Imap/ImapFolderSearch.cs
index 2de02cfe8e..f011550a0b 100644
--- a/MailKit/Net/Imap/ImapFolderSearch.cs
+++ b/MailKit/Net/Imap/ImapFolderSearch.cs
@@ -337,8 +337,8 @@ static string BuildSortOrder (IList<OrderBy> orderBy)
 
 		static async Task SearchMatchesAsync (ImapEngine engine, ImapCommand ic, int index, bool doAsync)
 		{
-			var uids = new UniqueIdSet (SortOrder.Ascending);
 			var results = (SearchResults) ic.UserData;
+			var uids = results.UniqueIds;
 			ImapToken token;
 			uint uid;
 
@@ -387,7 +387,6 @@ static async Task ESearchMatchesAsync (ImapEngine engine, ImapCommand ic, int in
 		{
 			var token = await engine.ReadTokenAsync (doAsync, ic.CancellationToken).ConfigureAwait (false);
 			var results = (SearchResults) ic.UserData;
-			UniqueIdSet uids = null;
 			int parenDepth = 0;
 			//bool uid = false;
 			string atom;
@@ -500,9 +499,10 @@ static async Task ESearchMatchesAsync (ImapEngine engine, ImapCommand ic, int in
 				case "ALL":
 					ImapEngine.AssertToken (token, ImapTokenType.Atom, ImapEngine.GenericUntaggedResponseSyntaxErrorFormat, "ESEARCH", token);
 
-					uids = ImapEngine.ParseUidSet (token, ic.Folder.UidValidity, ImapEngine.GenericItemSyntaxErrorFormat, atom, token);
+					var uids = ImapEngine.ParseUidSet (token, ic.Folder.UidValidity, ImapEngine.GenericItemSyntaxErrorFormat, atom, token);
 
 					results.Count = uids.Count;
+					results.UniqueIds = uids;
 					break;
 				default:
 					throw ImapEngine.UnexpectedToken (ImapEngine.GenericUntaggedResponseSyntaxErrorFormat, "ESEARCH", token);
@@ -510,8 +510,6 @@ static async Task ESearchMatchesAsync (ImapEngine engine, ImapCommand ic, int in
 
 				token = await engine.ReadTokenAsync (doAsync, ic.CancellationToken).ConfigureAwait (false);
 			} while (true);
-
-			results.UniqueIds = uids ?? new UniqueIdSet ();
 		}
 
 		async Task<SearchResults> SearchAsync (string query, bool doAsync, CancellationToken cancellationToken)
@@ -531,7 +529,7 @@ async Task<SearchResults> SearchAsync (string query, bool doAsync, CancellationT
 			if ((Engine.Capabilities & ImapCapabilities.ESearch) != 0)
 				ic.RegisterUntaggedHandler ("ESEARCH", ESearchMatchesAsync);
 			ic.RegisterUntaggedHandler ("SEARCH", SearchMatchesAsync);
-			ic.UserData = new SearchResults ();
+			ic.UserData = new SearchResults (SortOrder.Ascending);
 
 			Engine.QueueCommand (ic);
 
@@ -669,7 +667,7 @@ async Task<IList<UniqueId>> SearchAsync (SearchQuery query, bool doAsync, Cancel
 			// respond with "* SEARCH ..." instead of "* ESEARCH ..." even when using the extended
 			// search syntax.
 			ic.RegisterUntaggedHandler ("SEARCH", SearchMatchesAsync);
-			ic.UserData = new SearchResults ();
+			ic.UserData = new SearchResults (SortOrder.Ascending);
 
 			Engine.QueueCommand (ic);
 
diff --git a/MailKit/Search/SearchResults.cs b/MailKit/Search/SearchResults.cs
index 58976f0410..ec1bb39b7c 100644
--- a/MailKit/Search/SearchResults.cs
+++ b/MailKit/Search/SearchResults.cs
@@ -41,9 +41,10 @@ public class SearchResults
 		/// <remarks>
 		/// Creates a new <see cref="SearchResults"/>.
 		/// </remarks>
-		public SearchResults ()
+		/// <param name="order">The expected sort-order of the results.</param>
+		public SearchResults (SortOrder order = SortOrder.None)
 		{
-			UniqueIds = new UniqueId[0];
+			UniqueIds = new UniqueIdSet (order);
 		}
 
 		/// <summary>
diff --git a/UnitTests/Net/Imap/ImapClientTests.cs b/UnitTests/Net/Imap/ImapClientTests.cs
index 0ee52b5c0c..b93e7f26e5 100644
--- a/UnitTests/Net/Imap/ImapClientTests.cs
+++ b/UnitTests/Net/Imap/ImapClientTests.cs
@@ -3008,8 +3008,9 @@ public void TestDovecot ()
 				Assert.IsFalse (matches.Min.HasValue, "MIN should not be set");
 				Assert.AreEqual (0, matches.Count, "COUNT should not be set");
 				Assert.AreEqual (14, matches.UniqueIds.Count);
+				var expectedSortByReverseArrivalResults = new uint[] { 7, 14, 6, 13, 5, 12, 4, 11, 3, 10, 2, 9, 1, 8 };
 				for (int i = 0; i < matches.UniqueIds.Count; i++)
-					Assert.AreEqual (i + 1, matches.UniqueIds[i].Id);
+					Assert.AreEqual (expectedSortByReverseArrivalResults[i], matches.UniqueIds[i].Id);
 
 				destination.GetStreams (UniqueIdRange.All, GetStreamsCallback);
 				destination.GetStreams (new int[] { 0, 1, 2 }, GetStreamsCallback);
@@ -3632,8 +3633,9 @@ public async void TestDovecotAsync ()
 				Assert.IsFalse (matches.Min.HasValue, "MIN should not be set");
 				Assert.AreEqual (0, matches.Count, "COUNT should not be set");
 				Assert.AreEqual (14, matches.UniqueIds.Count);
+				var expectedSortByReverseArrivalResults = new uint[] { 7, 14, 6, 13, 5, 12, 4, 11, 3, 10, 2, 9, 1, 8 };
 				for (int i = 0; i < matches.UniqueIds.Count; i++)
-					Assert.AreEqual (i + 1, matches.UniqueIds[i].Id);
+					Assert.AreEqual (expectedSortByReverseArrivalResults[i], matches.UniqueIds[i].Id);
 
 				await destination.GetStreamsAsync (UniqueIdRange.All, GetStreamsCallback);
 				await destination.GetStreamsAsync (new int[] { 0, 1, 2 }, GetStreamsCallback);