diff --git a/dehydrated b/dehydrated
index c5b7e43..cfcdae8 100755
--- a/dehydrated
+++ b/dehydrated
@@ -1198,6 +1198,9 @@ sign_csr() {
     crt="$(signed_request "${certificate}" "" 4>"${resheaders}")"
 
     if [ -n "${PREFERRED_CHAIN:-}" ]; then
+      if ! (grep -Ei '^link:' "${resheaders}" | grep -q -Ei 'rel="alternate"'); then
+        _exiterr "Preferred chain defined but CA doesn't offer chain selection."
+      fi
       foundaltchain=0
       altcn="$(get_last_cn "${crt}")"
       altoptions="${altcn}"