diff --git a/parserstate.cpp b/parserstate.cpp
index 4acab62..edf3200 100644
--- a/parserstate.cpp
+++ b/parserstate.cpp
@@ -2,7 +2,7 @@
 
 using namespace Parser;
 
-Transition State::anywhere_rule( wchar_t ch )
+const Transition State::anywhere_rule( wchar_t ch )
 {
   if ( (ch == 0x18) || (ch == 0x1A)
        || ((0x80 <= ch) && (ch <= 0x8F))
@@ -26,7 +26,7 @@ Transition State::anywhere_rule( wchar_t ch )
   return Transition( Ignore(), NULL );
 }
 
-Transition State::input( wchar_t ch )
+const Transition State::input( wchar_t ch )
 {
   Transition any = anywhere_rule( ch );
   if ( any.next_state ) {
diff --git a/parserstate.hpp b/parserstate.hpp
index 203eadd..6ec27c7 100644
--- a/parserstate.hpp
+++ b/parserstate.hpp
@@ -7,14 +7,14 @@ namespace Parser {
   class State
   {
   protected:
-    virtual Transition input_state_rule( wchar_t ch ) { ch = ch; return Transition( Ignore(), NULL ); }
+    const virtual Transition input_state_rule( wchar_t ch ) { ch = ch; return Transition( Ignore(), NULL ); }
 
   private:
-    virtual Action enter( void ) { return Ignore(); };
-    virtual Action leave( void ) { return Ignore(); };
+    const virtual Action enter( void ) { return Ignore(); };
+    const virtual Action leave( void ) { return Ignore(); };
 
-    Transition input( wchar_t ch );
-    Transition anywhere_rule( wchar_t ch );
+    const Transition input( wchar_t ch );
+    const static Transition anywhere_rule( wchar_t ch );
 
   public:
     virtual ~State() {};