diff --git a/toxygen/middleware/callbacks.py b/toxygen/middleware/callbacks.py
index 41a5717..513cdd2 100644
--- a/toxygen/middleware/callbacks.py
+++ b/toxygen/middleware/callbacks.py
@@ -198,10 +198,7 @@ def file_recv_chunk(file_transfer_handler):
     """
     def wrapped(tox, friend_number, file_number, position, chunk, length, user_data):
         chunk = chunk[:length] if length else None
-        if length:
-            execute(file_transfer_handler.incoming_chunk, friend_number, file_number, position, chunk)
-        else:
-            invoke_in_main_thread(file_transfer_handler.incoming_chunk, friend_number, file_number, position, chunk)
+        execute(file_transfer_handler.incoming_chunk, friend_number, file_number, position, chunk)
 
     return wrapped
 
@@ -211,10 +208,7 @@ def file_chunk_request(file_transfer_handler):
     Outgoing chunk
     """
     def wrapped(tox, friend_number, file_number, position, size, user_data):
-        if size:
-            execute(file_transfer_handler.outgoing_chunk, friend_number, file_number, position, size)
-        else:
-            invoke_in_main_thread(file_transfer_handler.outgoing_chunk, friend_number, file_number, position, size)
+        invoke_in_main_thread(file_transfer_handler.outgoing_chunk, friend_number, file_number, position, size)
 
     return wrapped
 
diff --git a/toxygen/middleware/threads.py b/toxygen/middleware/threads.py
index 2e432b6..192f723 100644
--- a/toxygen/middleware/threads.py
+++ b/toxygen/middleware/threads.py
@@ -3,8 +3,13 @@ import threading
 import queue
 from utils import util
 import time
+from PyQt5 import QtCore
 
 
+# -----------------------------------------------------------------------------------------------------------------
+# Base threads
+# -----------------------------------------------------------------------------------------------------------------
+
 class BaseThread(threading.Thread):
 
     def __init__(self):
@@ -16,6 +21,21 @@ class BaseThread(threading.Thread):
         self.join()
 
 
+class BaseQThread(QtCore.QThread):
+
+    def __init__(self):
+        super().__init__()
+        self._stop_thread = False
+
+    def stop_thread(self):
+        self._stop_thread = True
+        self.wait()
+
+
+# -----------------------------------------------------------------------------------------------------------------
+# Toxcore threads
+# -----------------------------------------------------------------------------------------------------------------
+
 class InitThread(BaseThread):
 
     def __init__(self, tox, plugin_loader, settings):
@@ -53,7 +73,7 @@ class InitThread(BaseThread):
                 time.sleep(5)
 
 
-class ToxIterateThread(BaseThread):
+class ToxIterateThread(BaseQThread):
 
     def __init__(self, tox):
         super().__init__()
@@ -65,7 +85,7 @@ class ToxIterateThread(BaseThread):
             time.sleep(self._tox.iteration_interval() / 1000)
 
 
-class ToxAVIterateThread(BaseThread):
+class ToxAVIterateThread(BaseQThread):
 
     def __init__(self, toxav):
         super().__init__()
@@ -77,6 +97,10 @@ class ToxAVIterateThread(BaseThread):
             time.sleep(self._toxav.iteration_interval() / 1000)
 
 
+# -----------------------------------------------------------------------------------------------------------------
+# File transfers thread
+# -----------------------------------------------------------------------------------------------------------------
+
 class FileTransfersThread(BaseThread):
 
     def __init__(self):
@@ -115,6 +139,10 @@ def execute(func, *args, **kwargs):
     _thread.execute(func, *args, **kwargs)
 
 
+# -----------------------------------------------------------------------------------------------------------------
+# Invoking in main thread
+# -----------------------------------------------------------------------------------------------------------------
+
 class InvokeEvent(QtCore.QEvent):
     EVENT_TYPE = QtCore.QEvent.Type(QtCore.QEvent.registerEventType())