diff --git a/acinclude.m4 b/acinclude.m4
index 0563c130e..fdf87f084 100644
--- a/acinclude.m4
+++ b/acinclude.m4
@@ -303,6 +303,33 @@ END
 undefine([foo])
 ])
 
+dnl
+dnl Check if the prototype of a function is compatible with another one
+dnl
+
+dnl AC_PROTO_COMPAT(includes, function, prototype)
+
+AC_DEFUN(AC_PROTO_COMPAT, [
+AC_CACHE_CHECK([if $2 is compatible with system prototype],
+ac_cv_func_$2_proto_compat,
+AC_TRY_COMPILE([$1],
+[$3;],
+eval "ac_cv_func_$2_proto_compat=yes",
+eval "ac_cv_func_$2_proto_compat=no"))
+define([foo], translit($2, [a-z], [A-Z])[_PROTO_COMPATIBLE])
+if test "$ac_cv_func_$2_proto_compat" = yes; then
+	AC_DEFINE(foo)
+fi
+: << END
+@@@syms="$syms foo"@@@
+END
+undefine([foo])
+])
+
+dnl
+dnl Check if a particular struct has a particular field
+dnl
+
 dnl AC_HAVE_STRUCT_FIELD(includes, struct, type, field)
 AC_DEFUN(AC_HAVE_STRUCT_FIELD, [
 AC_MSG_CHECKING([if $2 has a field $4])