diff --git a/src/unvis.c b/src/unvis.c
index 166421a..0f40a27 100644
--- a/src/unvis.c
+++ b/src/unvis.c
@@ -564,12 +564,16 @@ strunvis(char *dst, const char *src)
  * NetBSD: 2012,  strnunvis(char *dst, size_t dlen, const char *src);
  */
 ssize_t
+strnunvis_openbsd(char *, const char *, size_t);
+ssize_t
 strnunvis_openbsd(char *dst, const char *src, size_t dlen)
 {
 	return strnunvisx(dst, dlen, src, 0);
 }
 libbsd_symver_default(strnunvis, strnunvis_openbsd, LIBBSD_0.2);
 
+int
+strnunvis_netbsd(char *, size_t, const char *);
 int
 strnunvis_netbsd(char *dst, size_t dlen, const char *src)
 {
diff --git a/src/vis.c b/src/vis.c
index c8e5ae8..f6261bc 100644
--- a/src/vis.c
+++ b/src/vis.c
@@ -733,12 +733,16 @@ strvis(char *mbdst, const char *mbsrc, int flags)
  * NetBSD: 2012,  strnvis(char *dst, size_t dlen, const char *src, int flag);
  */
 int
+strnvis_openbsd(char *, const char *, size_t, int);
+int
 strnvis_openbsd(char *mbdst, const char *mbsrc, size_t dlen, int flags)
 {
 	return istrsenvisxl(mbdst, &dlen, mbsrc, flags, "", NULL);
 }
 libbsd_symver_default(strnvis, strnvis_openbsd, LIBBSD_0.2);
 
+int
+strnvis_netbsd(char *, size_t, const char *, int);
 int
 strnvis_netbsd(char *mbdst, size_t dlen, const char *mbsrc, int flags)
 {