diff --git a/p2pfs/core/server.py b/p2pfs/core/server.py
index aa9cec5..a148614 100644
--- a/p2pfs/core/server.py
+++ b/p2pfs/core/server.py
@@ -16,7 +16,7 @@ class MessageServer:
         self._compressor = zstd.ZstdCompressor()
         self._decompressor = zstd.ZstdDecompressor()
 
-        self.is_running = True
+        self._is_running = True
 
     def start(self):
         self._sock.listen(5)
@@ -26,18 +26,18 @@ class MessageServer:
         self._server_started()
 
     def stop(self):
-        self.is_running = False
+        self._is_running = False
         self._sock.close()
 
     def _listen(self):
         try:
-            while self.is_running:
+            while self._is_running:
                 client, address = self._sock.accept()
                 logger.info('New connection from {}'.format(address))
                 self._client_connected(client)
                 threading.Thread(target=self._read_message, args=(client,)).start()
         except ConnectionAbortedError or OSError as e:
-            if self.is_running:
+            if self._is_running:
                 # if exception occurred during normal execution
                 logger.error(e)
             else: