diff --git a/squinnondation/peers.py b/squinnondation/peers.py
index ed4fdee..0f69edd 100644
--- a/squinnondation/peers.py
+++ b/squinnondation/peers.py
@@ -616,12 +616,14 @@ class User(Peer):
         This add the message in the history if not already done.
         Returns True iff the message was not already received previously.
         """
-        
+
+        self.data_lock.acquire()
         if (sender_id, nonce) not in self.received_messages:
             # If it is a new message, add it to recent_messages
             d = self.make_inundation_dict()
             pkt = Packet().construct(tlv)
             self.recent_messages[(sender_id, nonce)] = [pkt, time.time(), d]
+        self.data_lock.release()
 
         # in all cases, remove the sender from the list of neighbours to be inundated
         self.remove_from_inundation(relay, sender_id, nonce)
@@ -629,8 +631,10 @@ class User(Peer):
         if (sender_id, nonce) in self.received_messages:
             return False
 
+        self.data_lock.acquire()
         self.add_message(msg)  # for display purposes
         self.received_messages[(sender_id, nonce)] = Message(msg, sender_id, nonce)
+        self.data_lock.release()
         
         return True
 
@@ -650,6 +654,7 @@ class User(Peer):
         """
         Remove the sender from the list of neighbours to be inundated
         """
+        self.data_lock.acquire()
         if (sender_id, nonce) in self.recent_messages:
             # If a peer is late in its acknowledgement, the absence of the previous if causes an error.
             for addr in peer.addresses:
@@ -657,6 +662,7 @@ class User(Peer):
 
             if not self.recent_messages[(sender_id, nonce)][2]:  # If dictionnary is empty, remove the message
                 self.recent_messages.pop((sender_id, nonce), None)
+        self.data_lock.release()
 
     def clean_inundation(self) -> None:
         """
@@ -1073,6 +1079,7 @@ class Listener(Thread):
                 self.user.refresh_input()
                 self.user.refresh_emoji_pad()
 
+
 class Multicastlistener(Thread):
     """
     Used to listen on the multicast group to discover new people