diff --git a/include/channel.h b/include/channel.h
index ecdc03e8..9178718b 100644
--- a/include/channel.h
+++ b/include/channel.h
@@ -225,8 +225,8 @@ extern int is_banned(struct Channel *chptr, struct Client *who,
 		    struct membership *msptr, const char *, const char *, const char **);
 extern int is_quieted(struct Channel *chptr, struct Client *who,
 		     struct membership *msptr, const char *, const char *);
-extern int can_join(struct Client *source_p, struct Channel *chptr, char *key,
-		    const char **forward);
+extern int can_join(struct Client *source_p, struct Channel *chptr,
+		    const char *key, const char **forward);
 
 extern struct membership *find_channel_membership(struct Channel *, struct Client *);
 extern const char *find_channel_status(struct membership *msptr, int combine);
diff --git a/src/channel.c b/src/channel.c
index ac52b2b0..c55f9e21 100644
--- a/src/channel.c
+++ b/src/channel.c
@@ -664,7 +664,7 @@ is_quieted(struct Channel *chptr, struct Client *who, struct membership *msptr,
  * caveats      - this function should only be called on a local user.
  */
 int
-can_join(struct Client *source_p, struct Channel *chptr, char *key, const char **forward)
+can_join(struct Client *source_p, struct Channel *chptr, const char *key, const char **forward)
 {
 	rb_dlink_node *invite = NULL;
 	rb_dlink_node *ptr;