diff --git a/completion.h b/completion.h
index 9de1d91..947e9d8 100644
--- a/completion.h
+++ b/completion.h
@@ -13,7 +13,7 @@
  * @param input The current input
  * @return The completion object or NULL if an error occured
  */
-girara_completion_t* cc_open(girara_session_t* session, char* input);
+girara_completion_t* cc_open(girara_session_t* session, const char* input);
 
 /**
  * Completion for the bmarks command - Creates a list of bookmarks
@@ -22,7 +22,7 @@ girara_completion_t* cc_open(girara_session_t* session, char* input);
  * @param input The current input
  * @return The completion object or NULL if an error occured
  */
-girara_completion_t* cc_bookmarks(girara_session_t* session, char* input);
+girara_completion_t* cc_bookmarks(girara_session_t* session, const char* input);
 
 
 #endif // COMPLETION_H