diff --git a/lib/index.js b/lib/index.js
index e25856a..3eb30e4 100644
--- a/lib/index.js
+++ b/lib/index.js
@@ -14,6 +14,12 @@ module.exports.create = function(config) {
 			throw Error('listing zones not implemented');
 		},
 		set: function(data) {
+			var ch = data.challenge;
+			if (!ch.dnsZone) {
+				// zones() is not implemented for http-01 challenges,
+				// but it is almost always implemented for dns-01 challenges
+				throw new Error('No matching zone for ' + ch.dnsHost);
+			}
 			// console.info('Add TXT', data);
 			throw Error('setting TXT not implemented');
 		},