diff --git a/openair3/NAS/NR_UE/nr_nas_msg_sim.c b/openair3/NAS/NR_UE/nr_nas_msg_sim.c
index 2be24788b6..017150fea3 100644
--- a/openair3/NAS/NR_UE/nr_nas_msg_sim.c
+++ b/openair3/NAS/NR_UE/nr_nas_msg_sim.c
@@ -501,7 +501,7 @@ void generateSecurityModeComplete(as_nas_info_t *initialNasMsg)
 }
 
 void generateRegistrationComplete(as_nas_info_t *initialNasMsg, SORTransparentContainer               *sortransparentcontainer) {
-  int length = sizeof(fgs_nas_message_security_header_t);
+  int length = 0;
   int size = 0;
   fgs_nas_message_t nas_msg;
   nas_stream_cipher_t stream_cipher;
@@ -515,7 +515,7 @@ void generateRegistrationComplete(as_nas_info_t *initialNasMsg, SORTransparentCo
   sp_msg->header.security_header_type   = INTEGRITY_PROTECTED_AND_CIPHERED;
   sp_msg->header.message_authentication_code = 0;
   sp_msg->header.sequence_number        = 1;
-
+  int length = 7;
   sp_msg->plain.mm_msg.registration_complete.protocoldiscriminator = FGS_MOBILITY_MANAGEMENT_MESSAGE;
   length += 1;
   sp_msg->plain.mm_msg.registration_complete.securityheadertype    = PLAIN_5GS_MSG;