diff --git a/gui/builtinContextMenus/moduleAmmoChange.py b/gui/builtinContextMenus/moduleAmmoChange.py
index 7e3c72b84..991c0ede0 100644
--- a/gui/builtinContextMenus/moduleAmmoChange.py
+++ b/gui/builtinContextMenus/moduleAmmoChange.py
@@ -39,6 +39,7 @@ class ChangeModuleAmmo(ContextMenuCombined):
             ('r16', _t('Moon Uncommon')),
             ('r32', _t('Moon Rare')),
             ('r64', _t('Moon Exceptional')),
+            ('err', _t('Erratic')),
             ('misc', _t('Misc'))])
 
     def display(self, callingWindow, srcContext, mainItem, selection):
diff --git a/service/ammo.py b/service/ammo.py
index f38be0d96..84caa9217 100644
--- a/service/ammo.py
+++ b/service/ammo.py
@@ -177,7 +177,8 @@ class Ammo:
                 260: 'r8',
                 261: 'r16',
                 262: 'r32',
-                263: 'r64'}
+                263: 'r64',
+                859: 'err'}
 
             prelim = {}
             for charge in chargesFlat: