diff --git a/lib/consul/index.js b/lib/consul/index.js
index 5985a84..853d98b 100644
--- a/lib/consul/index.js
+++ b/lib/consul/index.js
@@ -154,7 +154,7 @@ var diff_kvs = function(write_kvs, delete_kvs, candidate_kvs, existing_kvs) {
     if (idx === -1) {
       // key does not exist in the current tree, so we must add it.
       write_kvs.push(kv);
-    } else if (kv.value.toString() !== existing_kvs[idx].value) {
+    } else if (kv.value === null || kv.value.toString() !== existing_kvs[idx].value) {
       // key exists in the current tree, but has a different value, so we must update it.
       write_kvs.push(kv);
       existing_kvs.splice(idx, 1);