diff --git a/src/spells/firewall.h b/src/spells/firewall.h
index 01602be21..8d0f15302 100644
--- a/src/spells/firewall.h
+++ b/src/spells/firewall.h
@@ -2,6 +2,7 @@
 
 struct castorder;
 struct unit;
+struct region;
 enum direction_t;
 
 void create_firewall(struct unit *mage, struct region *r, enum direction_t d, double force, int duration);