diff --git a/cf/vararray.m4 b/cf/vararray.m4
new file mode 100644
index 000000000..bc218d6ba
--- /dev/null
+++ b/cf/vararray.m4
@@ -0,0 +1,17 @@
+dnl
+dnl $Id$
+dnl
+dnl Test for variable size arrays.
+dnl
+
+AC_DEFUN([rk_C_VARARRAY], [
+	AC_CACHE_CHECK([if the compiler supports variable-length arrays],[rk_cv_c_vararray],[
+	AC_TRY_COMPILE([],
+		[int x = 0; { int y[x]; }],
+		[rk_cv_c_vararray=yes],
+		[rk_cv_c_vararray=no])])
+	if test "$rk_cv_c_vararray" = yes; then
+		AC_DEFINE([HAVE_VARIABLE_LENGTH_ARRAY], [1],
+			[Define if your compiler supports variable-length arrays.])
+	fi
+])