add test for volatile
diff --git a/configure.in b/configure.in
index 7201d84..6ca1f5a 100644
--- a/configure.in
+++ b/configure.in
@@ -214,7 +214,9 @@
 
 AC_CONST
 
-AC_COMPILE_CHECK([signed char], [], [signed char c;], [], AC_DEFINE(signed, []))
+AC_COMPILE_CHECK([lack of working volatile],[],[volatile int x; x = 0;],,AC_DEFINE(volatile,))
+
+AC_COMPILE_CHECK([lack of working signed char], [], [signed char c;],,AC_DEFINE(signed, []))
 
 AC_CHECKING(for prototypes)
 AC_TEST_PROGRAM([