diff --git a/src/merge.c b/src/merge.c
index 470352a..c82594c 100644
--- a/src/merge.c
+++ b/src/merge.c
@@ -255,7 +255,7 @@ COPY:	    			b = t;
  * when THRESHOLD/2 pairs compare with same sense.  (Only used when NATURAL
  * is defined.  Otherwise simple pairwise merging is used.)
  */
-void
+static void
 setup(u_char *list1, u_char *list2, size_t n, size_t size,
 	int (*cmp)(const void *, const void *))
 {