diff --git a/srsepc/src/hss/hss.cc b/srsepc/src/hss/hss.cc
index 4d12f8619..51405b969 100644
--- a/srsepc/src/hss/hss.cc
+++ b/srsepc/src/hss/hss.cc
@@ -486,8 +486,8 @@ hss::gen_update_loc_answer(uint64_t imsi, uint8_t* qci)
   std::map<uint64_t,hss_ue_ctx_t*>::iterator ue_ctx_it = m_imsi_to_ue_ctx.find(imsi);
   if(ue_ctx_it == m_imsi_to_ue_ctx.end())
   {
-    m_hss_log->info("User not found. IMSI: %015lu\n",imsi);
-    m_hss_log->console("User not found. IMSI: %015lu\n",imsi);
+    m_hss_log->info("User not found. IMSI: %015llu\n",imsi);
+    m_hss_log->console("User not found at HSS. IMSI: %015llu\n",imsi);
     return false;
   }
   hss_ue_ctx_t *ue_ctx = ue_ctx_it->second;
@@ -505,8 +505,8 @@ hss::get_k_amf_opc_sqn(uint64_t imsi, uint8_t *k, uint8_t *amf, uint8_t *opc, ui
   std::map<uint64_t,hss_ue_ctx_t*>::iterator ue_ctx_it = m_imsi_to_ue_ctx.find(imsi);
   if(ue_ctx_it == m_imsi_to_ue_ctx.end())
   {
-    m_hss_log->info("User not found. IMSI: %015lu\n",imsi);
-    m_hss_log->console("User not found. IMSI: %015lu\n",imsi);
+    m_hss_log->info("User not found. IMSI: %015llu\n",imsi);
+    m_hss_log->console("User not found at HSS. IMSI: %015llu\n",imsi);
     return false;
   }
   hss_ue_ctx_t *ue_ctx = ue_ctx_it->second;
diff --git a/srsepc/src/mme/nas.cc b/srsepc/src/mme/nas.cc
index a14b96f73..d6cb8d06d 100644
--- a/srsepc/src/mme/nas.cc
+++ b/srsepc/src/mme/nas.cc
@@ -100,8 +100,8 @@ nas::handle_attach_request( uint32_t enb_ue_s1ap_id,
     }
     nas_log->console("Attach request -- IMSI Style Attach request\n");
     nas_log->info("Attach request -- IMSI Style Attach request\n");
-    nas_log->console("Attach request -- IMSI: %015lu\n", imsi);
-    nas_log->info("Attach request -- IMSI: %015lu\n", imsi);
+    nas_log->console("Attach request -- IMSI: %015llu\n", imsi);
+    nas_log->info("Attach request -- IMSI: %015llu\n", imsi);
   } else if (attach_req.eps_mobile_id.type_of_id == LIBLTE_MME_EPS_MOBILE_ID_TYPE_GUTI) {
     m_tmsi = attach_req.eps_mobile_id.guti.m_tmsi;
     imsi = s1ap->find_imsi_from_m_tmsi(m_tmsi);
@@ -229,8 +229,8 @@ nas::handle_imsi_attach_request_unknown_ue( uint32_t enb_ue_s1ap_id,
 
   //Get Authentication Vectors from HSS
   if (!hss->gen_auth_info_answer(nas_ctx->m_emm_ctx.imsi, nas_ctx->m_sec_ctx.k_asme, nas_ctx->m_sec_ctx.autn, nas_ctx->m_sec_ctx.rand, nas_ctx->m_sec_ctx.xres)) {
-    nas_log->console("User not found. IMSI %015lu\n",nas_ctx->m_emm_ctx.imsi);
-    nas_log->info("User not found. IMSI %015lu\n",nas_ctx->m_emm_ctx.imsi);
+    nas_log->console("User not found. IMSI %015llu\n",nas_ctx->m_emm_ctx.imsi);
+    nas_log->info("User not found. IMSI %015llu\n",nas_ctx->m_emm_ctx.imsi);
     delete nas_ctx;
     return false;
   }
@@ -486,8 +486,8 @@ nas::handle_guti_attach_request_known_ue( nas *nas_ctx,
 
     //Get Authentication Vectors from HSS
     if (!hss->gen_auth_info_answer(emm_ctx->imsi, sec_ctx->k_asme, sec_ctx->autn, sec_ctx->rand, sec_ctx->xres)) {
-      nas_log->console("User not found. IMSI %015lu\n", emm_ctx->imsi);
-      nas_log->info("User not found. IMSI %015lu\n", emm_ctx->imsi);
+      nas_log->console("User not found. IMSI %015llu\n", emm_ctx->imsi);
+      nas_log->info("User not found. IMSI %015llu\n", emm_ctx->imsi);
       return false;
     }