diff --git a/src/vnet/sctp/sctp_output.c b/src/vnet/sctp/sctp_output.c
index 8863012..e76f67b 100644
--- a/src/vnet/sctp/sctp_output.c
+++ b/src/vnet/sctp/sctp_output.c
@@ -1334,8 +1334,10 @@
 sctp_push_hdr_i (sctp_connection_t * sctp_conn, vlib_buffer_t * b,
 		 sctp_state_t next_state)
 {
-  u16 data_len =
-    b->current_length + b->total_length_not_including_first_buffer;
+  u16 data_len = b->current_length;
+
+  if (b->flags & VLIB_BUFFER_TOTAL_LENGTH_VALID)
+    data_len += b->total_length_not_including_first_buffer;
 
   ASSERT (!b->total_length_not_including_first_buffer
 	  || (b->flags & VLIB_BUFFER_NEXT_PRESENT));