diff --git a/m4/visibility.m4 b/m4/visibility.m4
index 9f493bab..f0468e89 100644
--- a/m4/visibility.m4
+++ b/m4/visibility.m4
@@ -1,5 +1,5 @@
-# visibility.m4 serial 6
-dnl Copyright (C) 2005, 2008, 2010-2020 Free Software Foundation, Inc.
+# visibility.m4 serial 8
+dnl Copyright (C) 2005, 2008, 2010-2023 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
 dnl with or without modifications, as long as this notice is preserved.
@@ -58,6 +58,11 @@ AC_DEFUN([gl_VISIBILITY],
               extern __attribute__((__visibility__("default"))) int exportedvar;
               extern __attribute__((__visibility__("hidden"))) int hiddenfunc (void);
               extern __attribute__((__visibility__("default"))) int exportedfunc (void);
+              void dummyfunc (void);
+              int hiddenvar;
+              int exportedvar;
+              int hiddenfunc (void) { return 51; }
+              int exportedfunc (void) { return 1225736919; }
               void dummyfunc (void) {}
             ]],
             [[]])],