diff --git a/openair1/PHY/NR_TRANSPORT/nr_prach.c b/openair1/PHY/NR_TRANSPORT/nr_prach.c
index 34c647810d..6d82209148 100644
--- a/openair1/PHY/NR_TRANSPORT/nr_prach.c
+++ b/openair1/PHY/NR_TRANSPORT/nr_prach.c
@@ -174,7 +174,11 @@ void rx_nr_prach_ru(RU_t *ru,
 
   int msg1_frequencystart   = ru->config.prach_config.num_prach_fd_occasions_list[numRA].k1.value;
 
-  int sample_offset_slot = (prachStartSymbol==0?0:fp->ofdm_symbol_size*prachStartSymbol+fp->nb_prefix_samples0+fp->nb_prefix_samples*(prachStartSymbol-1));
+  int sample_offset_slot;
+  if (!(slot%(fp->slots_per_subframe/2)))
+    sample_offset_slot = (prachStartSymbol==0?0:fp->ofdm_symbol_size*prachStartSymbol+fp->nb_prefix_samples0+fp->nb_prefix_samples*(prachStartSymbol-1));
+  else
+    sample_offset_slot = (prachStartSymbol==0?0:prachStartSymbol*(fp->ofdm_symbol_size+fp->nb_prefix_samples));
   //to be checked for mu=0;
 
   LOG_D(PHY,"frame %d, slot %d: doing rx_nr_prach_ru for format %d, numRA %d, prachStartSymbol %d, prachOccasion %d\n",frame,slot,prachFormat,numRA,prachStartSymbol,prachOccasion);