diff --git a/lib/http_digest.h b/lib/http_digest.h
index f56024b33e4130522f8a57a244b9d14d0d0be09c..a8b33add83739c14a691585bcc9e3afd34a1704c 100644
--- a/lib/http_digest.h
+++ b/lib/http_digest.h
@@ -26,6 +26,7 @@
 typedef enum {
   CURLDIGEST_NONE, /* not a digest */
   CURLDIGEST_BAD,  /* a digest, but one we don't like */
+  CURLDIGEST_BADALGO, /* unsupported algorithm requested */
   CURLDIGEST_FINE, /* a digest we act on */
 
   CURLDIGEST_LAST  /* last entry in this enum, don't use */