diff --git a/Source/player.h b/Source/player.h
index 8a5fce29a..780a7dbff 100644
--- a/Source/player.h
+++ b/Source/player.h
@@ -990,7 +990,7 @@ void ModifyPlrStr(Player &player, int l);
 void ModifyPlrMag(Player &player, int l);
 void ModifyPlrDex(Player &player, int l);
 void ModifyPlrVit(Player &player, int l);
-void ModifyPlrManaCapacity(Player &player, int l, bool shiftCurrent);
+void ModifyPlrManaCapacity(Player &player, int delta, bool shiftCurrent);
 void SetPlayerHitPoints(Player &player, int val);
 void SetPlrStr(Player &player, int v);
 void SetPlrMag(Player &player, int v);