diff --git a/libcpp/include/cpplib.h b/libcpp/include/cpplib.h
index 8c81f9d..804132a 100644
--- a/libcpp/include/cpplib.h
+++ b/libcpp/include/cpplib.h
@@ -171,7 +171,8 @@
 enum c_lang {CLK_GNUC89 = 0, CLK_GNUC99, CLK_GNUC11,
 	     CLK_STDC89, CLK_STDC94, CLK_STDC99, CLK_STDC11,
 	     CLK_GNUCXX, CLK_CXX98, CLK_GNUCXX11, CLK_CXX11,
-	     CLK_GNUCXX14, CLK_CXX14, CLK_GNUCXX17, CLK_CXX17, CLK_ASM};
+	     CLK_GNUCXX14, CLK_CXX14, CLK_GNUCXX17, CLK_CXX17,
+	     CLK_GNUCXX2A, CLK_CXX2A, CLK_ASM};
 
 /* Payload of a NUMBER, STRING, CHAR or COMMENT token.  */
 struct GTY(()) cpp_string {