diff --git a/include/irc_dictionary.h b/include/irc_dictionary.h
index 0dac545..5d76284 100644
--- a/include/irc_dictionary.h
+++ b/include/irc_dictionary.h
@@ -33,7 +33,7 @@ struct DictionaryElement
 {
 	struct DictionaryElement *left, *right, *prev, *next;
 	void *data;
-	char *key;
+	const char *key;
 	int position;
 };
 
@@ -133,7 +133,7 @@ extern void irc_dictionary_foreach_next(struct Dictionary *dtree,
 /*
  * irc_dictionary_add() adds a key->value entry to the dictionary tree.
  */
-extern struct DictionaryElement *irc_dictionary_add(struct Dictionary *dtree, char *key, void *data);
+extern struct DictionaryElement *irc_dictionary_add(struct Dictionary *dtree, const char *key, void *data);
 
 /*
  * irc_dictionary_find() returns a struct DictionaryElement container from a dtree for key 'key'.
diff --git a/src/irc_dictionary.c b/src/irc_dictionary.c
index a99dede..bf9409b 100644
--- a/src/irc_dictionary.c
+++ b/src/irc_dictionary.c
@@ -704,7 +704,7 @@ struct DictionaryElement *irc_dictionary_find(struct Dictionary *dict, const cha
  * Side Effects:
  *     - data is inserted into the DTree.
  */
-struct DictionaryElement *irc_dictionary_add(struct Dictionary *dict, char *key, void *data)
+struct DictionaryElement *irc_dictionary_add(struct Dictionary *dict, const char *key, void *data)
 {
 	struct DictionaryElement *delem;