diff --git a/openair1/PHY/NR_UE_TRANSPORT/nr_initial_sync.c b/openair1/PHY/NR_UE_TRANSPORT/nr_initial_sync.c
index ba8c64d9f4..df35f14869 100644
--- a/openair1/PHY/NR_UE_TRANSPORT/nr_initial_sync.c
+++ b/openair1/PHY/NR_UE_TRANSPORT/nr_initial_sync.c
@@ -308,14 +308,15 @@ int nr_initial_sync(UE_nr_rxtx_proc_t *proc, PHY_VARS_NR_UE *ue, int n_frames)
         // every 7*(1<<mu) symbols there is a different prefix length (38.211 5.3.1)
         int n_symb_prefix0 = (ue->symbol_offset/(7*(1<<mu)))+1;
         sync_pos_frame = n_symb_prefix0*(fp->ofdm_symbol_size + fp->nb_prefix_samples0)+(ue->symbol_offset-n_symb_prefix0)*(fp->ofdm_symbol_size + fp->nb_prefix_samples);
+        // for a correct computation of frame number to sync with the one decoded at MIB we need to take into account in which of the n_frames we got sync
+        ue->init_sync_frame = n_frames - 1 - is;
+        // we also need to take into account the shift by samples_per_frame in case the if is true
         if (ue->ssb_offset < sync_pos_frame){
           ue->rx_offset = fp->samples_per_frame - sync_pos_frame + ue->ssb_offset;
-          ue->init_sync_frame = !is + 1;
+          ue->init_sync_frame += 1;
         }
-        else{
+        else
           ue->rx_offset = ue->ssb_offset - sync_pos_frame;
-          ue->init_sync_frame = !is;
-        }
       }   
 
     /*