diff --git a/scapy/layers/inet6.py b/scapy/layers/inet6.py
index b58978f4..c4a3084d 100644
--- a/scapy/layers/inet6.py
+++ b/scapy/layers/inet6.py
@@ -1073,6 +1073,7 @@ def defragment6(packets):
     q = res[0]
     nh = q[IPv6ExtHdrFragment].nh
     q[IPv6ExtHdrFragment].underlayer.nh = nh
+    q[IPv6ExtHdrFragment].underlayer.plen = len(fragmentable)
     del q[IPv6ExtHdrFragment].underlayer.payload
     q /= conf.raw_layer(load=fragmentable)