diff --git a/executables/nr-ru.c b/executables/nr-ru.c
index fa5ad3fa6e..97d865a930 100644
--- a/executables/nr-ru.c
+++ b/executables/nr-ru.c
@@ -1821,6 +1821,9 @@ void *ru_thread( void *param ) {
     if (ru->fh_south_in) ru->fh_south_in(ru,&frame,&slot);
     else AssertFatal(1==0, "No fronthaul interface at south port");
 
+    proc->frame_tx     = (proc->tti_rx > (fp->slots_per_frame-1-(fp->slots_per_subframe*sf_ahead))) ? (proc->frame_rx+1)&1023 : proc->frame_rx;
+    proc->tti_tx      = (proc->tti_rx + (fp->slots_per_subframe*sf_ahead))%fp->slots_per_frame;
+
     LOG_D(PHY,"AFTER fh_south_in - SFN/SL:%d%d RU->proc[RX:%d.%d TX:%d.%d] RC.gNB[0]:[RX:%d%d TX(SFN):%d]\n",
           frame,slot,
           proc->frame_rx,proc->tti_rx,