diff --git a/src/yaml/parsers.hh b/src/yaml/parsers.hh
index e1e03a4..5f52153 100644
--- a/src/yaml/parsers.hh
+++ b/src/yaml/parsers.hh
@@ -10,6 +10,7 @@
 #define __YAML_PARSERS_HH__
 
 #include <functional>
+#include <list>
 #include <memory>
 #include <stack>
 #include <sstream>
@@ -33,6 +34,11 @@ struct Parser
 
     typedef yaml_mark_t Mark;
 
+    struct TagDirective {
+        std::string handle;
+        std::string prefix;
+    };
+
     enum class Encoding {
         Any     = YAML_ANY_ENCODING,
         UTF8    = YAML_UTF8_ENCODING,