diff --git a/src/client.py b/src/client.py
--- a/src/client.py
+++ b/src/client.py
@@ -5,10 +5,11 @@ import logging as log
 from datetime import datetime
 
 import config as conf
+import status
 import stats
 from util import Progress
 from hashtree import HashTree,hashBlock
-from netnode import BaseConnection,NetNode,FailedConnection,LockedException
+from netnode import BaseConnection,NetNode,FailedConnection,LockedException,IncompatibleException
 
 
 class DeniedConnection(Exception): pass
@@ -50,8 +51,12 @@ class Client(NetNode):
 		self._outcoming.writeMsg(jsonData)
 		jsonData,binData=self._incoming.readMsg()
 		if jsonData["command"]=="deny":
+			if jsonData["status"]==status.incompatible.version:
+				raise DeniedConnection("Incompatible client version. Consider upgrading it.")
 			raise DeniedConnection()
 		assert jsonData["command"]=="init"
+		if jsonData["version"]<conf.lowestCompatible:
+			raise IncompatibleException("Incompatible server version. Consider upgrading it.")
 
 	## Asks server for node hashes to determine which are to be transferred.
 	#