diff --git a/src/Client.cs b/src/Client.cs
index af22c38..922925e 100644
--- a/src/Client.cs
+++ b/src/Client.cs
@@ -94,6 +94,9 @@ namespace WTelegram
 			})
 		{ }
 
+		public Client(Func<string, string> configProvider, byte[] startSession, Action<byte[]> saveSession)
+			: this(configProvider, new ActionStore(startSession, saveSession)) { }
+
 		/// <summary>Welcome to WTelegramClient! 🙂</summary>
 		/// <param name="configProvider">Config callback, is queried for: <b>api_id</b>, <b>api_hash</b>, <b>session_pathname</b></param>
 		/// <param name="sessionStore">if specified, must support initial Length &amp; Read() of a session, then calls to Write() the updated session. Other calls can be ignored</param>
diff --git a/src/Session.cs b/src/Session.cs
index b76ecbc..54c354c 100644
--- a/src/Session.cs
+++ b/src/Session.cs
@@ -192,4 +192,11 @@ namespace WTelegram
 			base.Write(_header, 0, 8);
 		}
 	}
+
+	// QWxp couldn't be bothered to write such a simple SessionStore, so here it is:
+	internal class ActionStore(byte[] startSession, Action<byte[]> saveSession) : MemoryStream(startSession ?? Array.Empty<byte>())
+	{
+		public override void Write(byte[] buffer, int offset, int count) => saveSession(buffer[offset..(offset + count)]);
+		public override void SetLength(long value) { }
+	}
 }
\ No newline at end of file