diff --git a/lib/index.js b/lib/index.js
index 6b38df6..834208e 100644
--- a/lib/index.js
+++ b/lib/index.js
@@ -237,6 +237,11 @@ CloudFront.prototype.deleteDistribution = function(distribution, etag, opts, cb)
 };
 
 CloudFront.prototype.listDistributions = function(opts, cb) {
+  if (arguments.length === 1) {
+    cb = opts;
+    opts = {};
+  }
+
   var self = this;
   this.request('GET', listOptsToPath('distribution', opts), function(err, body) {
     if (err) return cb(err);
@@ -273,6 +278,11 @@ CloudFront.prototype.getInvalidation = function(distribution, id, cb) {
 };
 
 CloudFront.prototype.listInvalidations = function(distribution, opts, cb) {
+  if (arguments.length === 2) {
+    cb = opts;
+    opts = {};
+  }
+
   var self = this;
   this.request('GET', listOptsToPath('distribution/' + distribution + '/invalidation', opts), function(err, body) {
     if (err) return cb(err);