diff --git a/src/write.c b/src/write.c
index 9227505d6..ce9afc142 100644
--- a/src/write.c
+++ b/src/write.c
@@ -6,7 +6,7 @@
 static int cost(struct obj *) NONNULLARG1;
 static boolean label_known(int, struct obj *) NO_NNARGS;
 static int write_ok(struct obj *) NO_NNARGS;
-static char *new_book_description(int, char *) NONNULL NONNULLARG1;
+static char *new_book_description(int, char *) NONNULL NONNULLPTRS;
 
 /*
  * returns basecost of a scroll or a spellbook