diff --git a/lib/trace-agent.js b/lib/trace-agent.js
index d70c56e61..f90548ca8 100644
--- a/lib/trace-agent.js
+++ b/lib/trace-agent.js
@@ -172,7 +172,7 @@ TraceAgent.prototype.shouldTrace = function(name) {
  */
 TraceAgent.prototype.createRootSpanData = function(name, traceId, parentId) {
   traceId = traceId || (uuid.v4().split('-').join(''));
-  parentId = parentId || 0;
+  parentId = parentId || '0';
   var trace = new Trace(0, traceId); // project number added later
   var spanData = new SpanData(this, trace, name, parentId, true);
   cls.setRootContext(spanData);
@@ -208,7 +208,7 @@ TraceAgent.prototype.parseContextFromHeader = function(str) {
   }
   return {
     traceId: matches[1],
-    spanId: Number(matches[2]),
+    spanId: matches[2],
     options: matches[3]
   };
 };
diff --git a/test/test-trace-agent.js b/test/test-trace-agent.js
index 482c6802a..f79406c9e 100644
--- a/test/test-trace-agent.js
+++ b/test/test-trace-agent.js
@@ -65,7 +65,7 @@ describe('Trace Agent', function() {
             options.headers[constants.TRACE_CONTEXT_HEADER_NAME]);
         assert.equal(parsed.traceId, 1);
         assert.equal(parsed.spanId, spanId);
-        assert.equal(typeof parsed.spanId, 'number');
+        assert.equal(typeof parsed.spanId, 'string');
         assert.equal(parsed.options, 1);
       });
     });
@@ -92,6 +92,16 @@ describe('Trace Agent', function() {
         assert.equal(result.options, '1');
       });
 
+      it('should return expected values:' +
+          '123456/123456123456123456123456123456123456;o=1', function() {
+        var result = agent.parseContextFromHeader(
+          '123456/123456123456123456123456123456123456;o=1');
+        assert(result);
+        assert.equal(result.traceId, '123456');
+        assert.equal(result.spanId, '123456123456123456123456123456123456');
+        assert.equal(result.options, '1');
+      });
+
       it('should return expected values: 123456/667', function() {
         var result = agent.parseContextFromHeader(
           '123456/667');