diff -r 18941b52c8d7 -r 5ef6780b1c05 hedgewars/uConsts.pas
--- a/hedgewars/uConsts.pas	Wed Oct 18 02:17:03 2017 +0200
+++ b/hedgewars/uConsts.pas	Wed Oct 18 03:19:43 2017 +0200
@@ -275,7 +275,8 @@
     gmDelete         = $00010000;
     gmAllStoppable = gmLeft or gmRight or gmUp or gmDown or gmAttack or gmPrecise;
 
-    cMaxSlotIndex       = 9;
+    cMaxSlotIndex       = 10;
+    cHiddenSlotIndex    = cMaxSlotIndex; // slot for hidden ammo types, not visible and has no key
     cMaxSlotAmmoIndex   = 5;
 
     // ai hints