diff --git a/test/testutil.h b/test/testutil.h
index 39b6d0e..cc2f153 100644
--- a/test/testutil.h
+++ b/test/testutil.h
@@ -107,7 +107,7 @@
  * TEST_CASE_NAME is defined as the name of the test case function where
  * possible; otherwise we get by with the file name and line number.
  */
-# if __STDC_VERSION__ < 199901L
+# if !defined(__STDC_VERSION__) || __STDC_VERSION__ < 199901L
 #  if defined(_MSC_VER)
 #   define TEST_CASE_NAME __FUNCTION__
 #  else