diff --git a/lib/loggly/common.js b/lib/loggly/common.js
index 633f715..361c890 100644
--- a/lib/loggly/common.js
+++ b/lib/loggly/common.js
@@ -148,10 +148,18 @@ common.loggly = function () {
 // ### function serialize (obj, key)
 // #### @obj {Object|literal} Object to serialize
 // #### @key {string} **Optional** Optional key represented by obj in a larger object
+// #### @stack {Array} **Optional** Internal array used to avoid cycles
 // Performs simple comma-separated, `key=value` serialization for Loggly when
 // logging for non-JSON values.
 //
-common.serialize = function (obj, key) {
+common.serialize = function (obj, key, stack) {
+  if (stack && stack.includes(obj)) {
+    return (key ? key + '=' : '') + '<Circular>';
+  }
+
+  var updatedStack = stack ? stack.slice() : [];
+  updatedStack.unshift(obj);
+
   if (obj === null) {
     obj = 'null';
   }
@@ -175,7 +183,7 @@ common.serialize = function (obj, key) {
       msg += keys[i] + '=[';
 
       for (var j = 0, l = obj[keys[i]].length; j < l; j++) {
-        msg += common.serialize(obj[keys[i]][j]);
+        msg += common.serialize(obj[keys[i]][j], null, updatedStack);
         if (j < l - 1) {
           msg += ', ';
         }
@@ -184,7 +192,7 @@ common.serialize = function (obj, key) {
       msg += ']';
     }
     else {
-      msg += common.serialize(obj[keys[i]], keys[i]);
+      msg += common.serialize(obj[keys[i]], keys[i], updatedStack);
     }
 
     if (i < length - 1) {
diff --git a/test/common-test.js b/test/common-test.js
index ac5d3f4..76dfcc0 100644
--- a/test/common-test.js
+++ b/test/common-test.js
@@ -27,6 +27,20 @@ vows.describe('node-loggly/common').addBatch({
       "should return a deep clone of the object": function (clone) {
         assert.isFalse(this.obj.deep === clone.deep);
       }
+    },
+
+    "the serialize() method": {
+      topic: function () {
+        this.obj = {
+          name: 'cyclical',
+        };
+
+        this.obj.cycle = this.obj;
+        return common.serialize(this.obj);
+      },
+      "should handle objects containing cyclical references": function (serialized) {
+        assert.equal("name=cyclical, cycle=<Circular>", serialized);
+      }
     }
   }
 }).export(module);
\ No newline at end of file