diff --git a/lib/web3/formatters.js b/lib/web3/formatters.js
index 4388f64..22a828b 100644
--- a/lib/web3/formatters.js
+++ b/lib/web3/formatters.js
@@ -159,6 +159,9 @@ var inputPostFormatter = function(post) {
     post.priority = utils.fromDecimal(post.priority);
 
     // fallback
+    if (post.topics == undefined) {
+        post.topics = []
+    }
     if (!utils.isArray(post.topics)) {
         post.topics = [post.topics];
     }