address_is_users (const char *address, notmuch_config_t *config)
 {
     const char *primary;
-    char **other;
+    const char **other;
     size_t i, other_len;
 
     primary = notmuch_config_get_user_primary_email (config);
 guess_from_received_header (notmuch_config_t *config, notmuch_message_t *message)
 {
     const char *received,*primary,*by;
-    char **other,*tohdr;
+    const char **other;
+    char *tohdr;
     char *mta,*ptr,*token;
     char *domain=NULL;
     char *tld=NULL;
 
     char *response = NULL;
     size_t response_size;
     notmuch_config_t *config;
-    char **old_other_emails;
+    const char **old_other_emails;
     size_t old_other_emails_len;
     GPtrArray *other_emails;
     unsigned int i;