diff --git a/infrastructure-centred/owlps-aggregator/owlps-aggregatord.c b/infrastructure-centred/owlps-aggregator/owlps-aggregatord.c
index e181629..4984355 100644
--- a/infrastructure-centred/owlps-aggregator/owlps-aggregatord.c
+++ b/infrastructure-centred/owlps-aggregator/owlps-aggregatord.c
@@ -756,6 +756,12 @@ ap_list* find_ap(unsigned char mac_addr_bytes[6])
  */
 ap_list* add_ap_front(unsigned char mac_addr_bytes[6])
 {
+#ifdef DEBUG
+  char *mac = mac_bytes_to_string(mac_addr_bytes) ;
+  fprintf(stderr, "Creating AP with MAC address « %s »...\n", mac) ;
+  free(mac) ;
+#endif // DEBUG
+
   ap_list *ap = malloc(sizeof(ap_list)) ;
   memcpy(ap->mac_addr_bytes, mac_addr_bytes, 6) ;
   update_ap_seen(ap) ;
@@ -861,6 +867,13 @@ void delete_old_aps()
  */
 void delete_ap(ap_list *ap)
 {
+#ifdef DEBUG
+  assert(ap) ;
+  char *mac = mac_bytes_to_string(token_aps->mac_addr_bytes) ;
+  fprintf(stderr, "Deleting AP « %s »...\n", mac) ;
+  free(mac) ;
+#endif // DEBUG
+
   unlink_ap(ap) ;
   free(ap) ;
   --nb_aps ;
@@ -873,11 +886,13 @@ void delete_ap(ap_list *ap)
  */
 void unlink_ap(ap_list *ap)
 {
-  assert(ap) ;
   ap_list
-    *ap_previous = ap->previous,
-    *ap_next = ap->next ;
+    *ap_previous,
+    *ap_next ;
 
+  assert(ap) ;
+  ap_previous = ap->previous ;
+  ap_next = ap->next ;
   assert(ap_previous) ;
   assert(ap_next) ;
 
@@ -1076,8 +1091,8 @@ void print_usage()
          " requests (default\t%d microseconds).\n"
 
          "Autocalibration options:\n"
-         "\t-A\tEnable autocalibration (default: disabled).\n"
-         "\t-a port\tPort on which autocalibration data"
+         "\t-A\t\t\tEnable autocalibration (default: disabled).\n"
+         "\t-a port\t\t\tPort on which autocalibration data"
          " are exchanged with the listeners (default: %d).\n"
          "\t-K ap_keep_timeout\tInactive APs are kept during"
          " 'ap_keep_timeout' seconds (default: %d s).\n"