/* This is a private header; never even think of including this directly! */
-#if __INCLUDE_LEVEL__ <= 1
-#error "Do not include _sd-common.h directly; it is a private header."
+#if defined(__INCLUDE_LEVEL__) && __INCLUDE_LEVEL__ <= 1
+# error "Do not include _sd-common.h directly; it is a private header."
#endif
#ifndef _sd_printf_