diff --git a/m4/getopt.m4 b/m4/getopt.m4
index 595483d58..e291e0c66 100644
--- a/m4/getopt.m4
+++ b/m4/getopt.m4
@@ -1,5 +1,5 @@
 # getopt.m4 serial 47
-dnl Copyright (C) 2002-2006, 2008-2020 Free Software Foundation, Inc.
+dnl Copyright (C) 2002-2006, 2008-2020, 2022 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.
@@ -363,13 +363,9 @@ dnl is ambiguous with environment values that contain newlines.
 
 AC_DEFUN([gl_GETOPT_SUBSTITUTE_HEADER],
 [
-  AC_CHECK_HEADERS_ONCE([sys/cdefs.h])
-  if test $ac_cv_header_sys_cdefs_h = yes; then
-    HAVE_SYS_CDEFS_H=1
-  else
-    HAVE_SYS_CDEFS_H=0
-  fi
-  AC_SUBST([HAVE_SYS_CDEFS_H])
+  # pretend HAVE_SYS_CDEFS_H is always 0 including <sys/defs.h> isn't
+  # really necessary and causes warning on Alpine Linux.
+  AC_SUBST([HAVE_SYS_CDEFS_H], [0])
 
   AC_DEFINE([__GETOPT_PREFIX], [[rpl_]],
     [Define to rpl_ if the getopt replacement functions and variables