diff --git a/RNS/Link.py b/RNS/Link.py
index dd6d1e0..12523c4 100644
--- a/RNS/Link.py
+++ b/RNS/Link.py
@@ -459,6 +459,7 @@ class Link:
 
     def update_mdu(self):
         self.mdu = self.mtu - RNS.Reticulum.HEADER_MAXSIZE - RNS.Reticulum.IFAC_MIN_SIZE
+        self.mdu = math.floor((self.mtu-RNS.Reticulum.IFAC_MIN_SIZE-RNS.Reticulum.HEADER_MINSIZE-RNS.Identity.TOKEN_OVERHEAD)/RNS.Identity.AES128_BLOCKSIZE)*RNS.Identity.AES128_BLOCKSIZE - 1
         RNS.log(f"Link MDU updated to {self.mdu}", RNS.LOG_DEBUG) # TODO: Remove debug
 
     def rtt_packet(self, packet):