diff --git a/libcpp/include/cpplib.h b/libcpp/include/cpplib.h
index ffde40e..adc6cf1 100644
--- a/libcpp/include/cpplib.h
+++ b/libcpp/include/cpplib.h
@@ -813,6 +813,8 @@
 #define CPP_DL_ICE		0x04
 /* An informative note following a warning.  */
 #define CPP_DL_NOTE		0x05
+/* A fatal error.  */
+#define CPP_DL_FATAL		0x06
 
 /* Output a diagnostic of some kind.  */
 extern bool cpp_error (cpp_reader *, int, const char *msgid, ...)