diff --git a/include/extern.h b/include/extern.h
index 741087c7f..4887d8884 100644
--- a/include/extern.h
+++ b/include/extern.h
@@ -938,7 +938,7 @@ E void FDECL(mimic_hit_msg, (struct monst *, SHORT_P));
 E void FDECL(mkmonmoney, (struct monst *, long));
 #endif
 E void FDECL(bagotricks, (struct obj *));
-E boolean FDECL(propagate, (int, BOOLEAN_P));
+E boolean FDECL(propagate, (int, BOOLEAN_P,BOOLEAN_P));
 
 /* ### mapglyph.c ### */