diff --git a/lib/association.js b/lib/association.js
index 0fdb4a2..8097b9b 100644
--- a/lib/association.js
+++ b/lib/association.js
@@ -47,7 +47,7 @@ class Association extends EventEmitter {
     this.rto_min = defs.NET_SCTP.rto_min
     this.rto_max = defs.NET_SCTP.rto_max
 
-    const PMTU = 1500 // TODO
+    const PMTU = defs.NET_SCTP.PMTU || 1500 // TODO
 
     this.peer_rwnd = 0
 
diff --git a/lib/defs.js b/lib/defs.js
index 9ce1517..a43c844 100644
--- a/lib/defs.js
+++ b/lib/defs.js
@@ -23,7 +23,8 @@ const NET_SCTP = {
   max_init_retransmits: 8,
   hb_interval: 30000,
   sack_timeout: 180,
-  sack_freq: 2
+  sack_freq: 2,
+  PMTU: 1500
 }
 
 const CAUSE_CODES = {