diff --git a/internal/httpapi/routes_lookup.go b/internal/httpapi/routes_lookup.go
index 2ea2d90..a20c718 100644
--- a/internal/httpapi/routes_lookup.go
+++ b/internal/httpapi/routes_lookup.go
@@ -27,7 +27,7 @@ func (s *Server) handleLookup(w http.ResponseWriter, r *http.Request) {
 	res, err := lookup.Lookup(s.store, a.TenantID, q)
 	if err != nil {
 		if errors.Is(err, store.ErrInvalidInput) {
-			writeProblem(w, http.StatusBadRequest, "Bad Request", err.Error())
+			writeProblem(w, http.StatusBadRequest, "Bad Request", "query must be an IP address or FQDN")
 			return
 		}
 		writeStoreErr(w, err)