-#if _PDCLIB_C_VERSION != C99
-#error As of the current release, PDCLib only supports ISO/IEC 9899:1999 (C99).
+#if _PDCLIB_C_VERSION != 99
+#warning Up to and including v1.x, PDCLib is only aiming at ISO/IEC 9899:1999 (C99).
+#warning PDCLib might not be fully conforming to either C89 or C95 prior to v2.x.