diff --git a/src/share/win_utf8_io/win_utf8_io.c b/src/share/win_utf8_io/win_utf8_io.c
index 2bf0c93..6b5c56c 100644
--- a/src/share/win_utf8_io/win_utf8_io.c
+++ b/src/share/win_utf8_io/win_utf8_io.c
@@ -103,7 +103,7 @@
 	return widestr;
 }
 
-void set_filename_utf8(int b);
+static void set_filename_utf8(int b);
 
 /* retrieve WCHAR commandline, expand wildcards and convert everything to UTF-8 */
 int get_utf8_argv(int *argc, char ***argv)