diff --git a/lib/tempname.h b/lib/tempname.h
index 7972562..7ced9a9 100644
--- a/lib/tempname.h
+++ b/lib/tempname.h
@@ -46,5 +46,7 @@

    We use a clever algorithm to get hard-to-predict names. */
 extern int gen_tempname (char *tmpl, int suffixlen, int flags, int kind);
+extern int gen_tempname_len (char *tmpl, int suffixlen, int flags, int kind,
+                             size_t x_suffix_len);

 #endif /* GL_TEMPNAME_H */