diff --git a/lisp/clark.lisp b/lisp/clark.lisp
index 03c8614..d65fa87 100644
--- a/lisp/clark.lisp
+++ b/lisp/clark.lisp
@@ -22,7 +22,7 @@
 (defvar *db* nil
   "The database connection.")
 
-(defvar *help-messages* nil
+(defparameter *help-messages* nil
   "Help texts for commands.")
 
 (defvar *max-command-name-length* 0