diff --git a/cf/check-getpwnam_r-posix.m4 b/cf/check-getpwnam_r-posix.m4
index aab9eaf..bd51b93 100644
--- a/cf/check-getpwnam_r-posix.m4
+++ b/cf/check-getpwnam_r-posix.m4
@@ -3,7 +3,7 @@ dnl
 dnl check for getpwnam_r, and if it's posix or not
 
 AC_DEFUN([AC_CHECK_GETPWNAM_R_POSIX],[
-AC_FIND_FUNC_NO_LIBS(getpwnam_r,c_r)
+AC_FIND_FUNC_NO_LIBS(getpwnam_r,c_r,[#include <pwd.h>],[0, 0, 0, 0, 0])
 if test "$ac_cv_func_getpwnam_r" = yes; then
 	AC_CACHE_CHECK(if getpwnam_r is posix,ac_cv_func_getpwnam_r_posix,
 	ac_libs="$LIBS"