diff --git a/src/gsm_rlcmac.cpp b/src/gsm_rlcmac.cpp
index 7006900..39f328d 100644
--- a/src/gsm_rlcmac.cpp
+++ b/src/gsm_rlcmac.cpp
@@ -3480,7 +3480,7 @@
 
 static const
 CSN_DESCR_BEGIN (PMR_AdditionsR5_t)
-  M_NEXT_EXIST  (PMR_AdditionsR5_t, Exist_GRNTI, 4),
+  M_NEXT_EXIST  (PMR_AdditionsR5_t, Exist_GRNTI, 3),
   M_UINT        (PMR_AdditionsR5_t,  GRNTI,  4),
   M_NEXT_EXIST_OR_NULL (PMR_AdditionsR5_t, Exist_AdditionsR8, 1),
   M_TYPE        (PMR_AdditionsR5_t, AdditionsR8, PMR_AdditionsR8_t),