diff --git a/m4/ac_attribute.m4 b/m4/ac_attribute.m4
new file mode 100644
index 000000000..46c1a4229
--- /dev/null
+++ b/m4/ac_attribute.m4
@@ -0,0 +1,14 @@
+
+AC_DEFUN([AC_C___ATTRIBUTE__],
+[
+  AC_MSG_CHECKING(for __attribute__)
+  AC_CACHE_VAL(ac_cv___attribute__, [
+  AC_TRY_COMPILE([#include <stdlib.h>],
+  [int func(int x); int foo(int x __attribute__ ((unused))) { exit(1); }],
+  ac_cv___attribute__=yes, ac_cv___attribute__=no)])
+  if test "$ac_cv___attribute__" = "yes"; then
+    AC_DEFINE(HAVE___ATTRIBUTE__, 1, [Define to 1 if your compiler has __attribute__])
+  fi
+  AC_MSG_RESULT($ac_cv___attribute__)
+])
+