diff --git a/src/general.c b/src/general.c

index c4d1f55..bacdd81 100644

--- a/src/general.c

+++ b/src/general.c

@@ -272,6 +272,8 @@ static const struct sinfo {

   SINFO( nodata,              "No such data"                                 )

 };

+static const char *unknown_error_str = "unknown error code";

+

 static int si_compar(const void *key, const void *elem) {

   const adns_status *st= key;

   const struct sinfo *si= elem;

@@ -288,7 +290,7 @@ const char *adns_strerror(adns_status st) {

   const struct sinfo *si;

   si= findsinfo(st);

-  return si->string;

+  return (si == NULL) ? unknown_error_str : si->string;

 }

 const char *adns_errabbrev(adns_status st) {