diff --git a/RNS/Transport.py b/RNS/Transport.py
index cc773e1..3cd2095 100755
--- a/RNS/Transport.py
+++ b/RNS/Transport.py
@@ -758,6 +758,15 @@ class Transport:
                 RNS.log(str(interface)+" with IFAC enabled received packet without access code, dropping.", RNS.LOG_EXTREME)
                 return
 
+        else:
+            # If the interface does not have IFAC enabled,
+            # check the received packet IFAC flag.
+            if raw[0] & 0x80 == 0x80:
+                # If the flag is set, drop the packet
+                # TODO: Remove log statements
+                RNS.log(str(interface)+" with IFAC disabled received packet with access code, dropping.", RNS.LOG_EXTREME)
+                return
+
         while (Transport.jobs_running):
             sleep(0.01)