diff --git a/openair1/SCHED/phy_procedures_lte_eNb.c b/openair1/SCHED/phy_procedures_lte_eNb.c
index d1363eaeb9a361a2ba1e9f2a72b459db5ac41d29..ece4b6eca554c6a353c05c8df9a71b64482ea387 100644
--- a/openair1/SCHED/phy_procedures_lte_eNb.c
+++ b/openair1/SCHED/phy_procedures_lte_eNb.c
@@ -1765,6 +1765,7 @@ void fill_uci_harq_indication(PHY_VARS_eNB *eNB,
 			      uint16_t tdd_multiplexing_mask) {
 
   int UE_id=find_dlsch(uci->rnti,eNB,SEARCH_EXIST);
+  AssertFatal(UE_id>=0,"UE_id doesn't exist\n");
 
 
   pthread_mutex_lock(&eNB->UL_INFO_mutex);