diff --git a/openair1/SIMULATION/NR_PHY/dlsim.c b/openair1/SIMULATION/NR_PHY/dlsim.c
index d3a6c0fc06..31313aae22 100644
--- a/openair1/SIMULATION/NR_PHY/dlsim.c
+++ b/openair1/SIMULATION/NR_PHY/dlsim.c
@@ -140,6 +140,7 @@ int generate_dlsch_header(unsigned char *mac_header,
                           unsigned char short_padding,
                           unsigned short post_padding){return 0;}
 
+// Dummy function to avoid linking error at compilation of nr-dlsim
 int is_x2ap_enabled(void)
 {
   return 0;
diff --git a/openair1/SIMULATION/NR_PHY/prachsim.c b/openair1/SIMULATION/NR_PHY/prachsim.c
index dd78524ae1..9b1e9be703 100644
--- a/openair1/SIMULATION/NR_PHY/prachsim.c
+++ b/openair1/SIMULATION/NR_PHY/prachsim.c
@@ -100,6 +100,7 @@ rrc_gNB_process_GTPV1U_CREATE_TUNNEL_RESP(
 
 int8_t nr_mac_rrc_data_ind_ue(const module_id_t module_id, const int CC_id, const uint8_t gNB_index, const int8_t channel, const uint8_t* pduP, const sdu_size_t pdu_len) {return 0;}
 
+// Dummy function to avoid linking error at compilation of nr-prachsim
 int is_x2ap_enabled(void)
 {
   return 0;
diff --git a/openair1/SIMULATION/NR_PHY/ulsim.c b/openair1/SIMULATION/NR_PHY/ulsim.c
index 135b59066b..5494e64eca 100644
--- a/openair1/SIMULATION/NR_PHY/ulsim.c
+++ b/openair1/SIMULATION/NR_PHY/ulsim.c
@@ -119,6 +119,7 @@ rrc_gNB_process_GTPV1U_CREATE_TUNNEL_RESP(
   return 0;
 }
 
+// Dummy function to avoid linking error at compilation of nr-ulsim
 int is_x2ap_enabled(void)
 {
   return 0;