diff --git a/src/util/spell_checker.hpp b/src/util/spell_checker.hpp
index 3802d069..a07117b1 100644
--- a/src/util/spell_checker.hpp
+++ b/src/util/spell_checker.hpp
@@ -17,7 +17,7 @@ DECLARE_POINTER_TYPE(SpellChecker);
 #ifdef UNICODE
 	typedef wxCharBuffer CharBuffer;
 #else
-	typedef char* CharBuffer;
+	typedef const char* CharBuffer;
 #endif
 
 // ----------------------------------------------------------------------------- : Spell checker