diff --git a/src/Grammar.cpp b/src/Grammar.cpp
index 28fab208..062a9a80 100644
--- a/src/Grammar.cpp
+++ b/src/Grammar.cpp
@@ -32,6 +32,7 @@
 
 ////////////////////////////////////////////////////////////////////////////////
 Grammar::Grammar ()
+: _debug (false)
 {
 }
 
@@ -185,6 +186,12 @@ std::vector <std::vector <std::string>> Grammar::augmented () const
   return results;
 }
 
+////////////////////////////////////////////////////////////////////////////////
+void Grammar::debug (bool value)
+{
+  _debug = value;
+}
+
 ////////////////////////////////////////////////////////////////////////////////
 std::string Grammar::dump () const
 {
diff --git a/src/Grammar.h b/src/Grammar.h
index 0ed932e8..89ab608a 100644
--- a/src/Grammar.h
+++ b/src/Grammar.h
@@ -42,6 +42,7 @@ public:
   std::vector <std::string> rules () const;
   std::vector <std::string> terminals () const;
   std::vector <std::vector <std::string>> augmented () const;
+  void debug (bool);
   std::string dump () const;
 
 protected:
@@ -69,6 +70,7 @@ private:
 private:
   std::string _start;
   std::map <std::string, Grammar::Rule> _rules;
+  bool _debug;
 };
 
 #endif