diff --git a/src/trace-span.js b/src/trace-span.js
index a10bfdf63..80bdaed62 100644
--- a/src/trace-span.js
+++ b/src/trace-span.js
@@ -16,6 +16,8 @@
 
 'use strict';
 
+var util = require('util');
+
 /**
  * Creates a trace span object.
  * @constructor
@@ -37,7 +39,7 @@ function TraceSpan(name, spanId, parentSpanId) {
  * @param {string} value The new value of the label.
  */
 TraceSpan.prototype.setLabel = function(key, value) {
-  this.labels[key] = '' + value;
+  this.labels[key] = typeof value === 'object' ? util.inspect(value) : '' + value;
 };
 
 
diff --git a/test/hooks/test-trace-grpc.js b/test/hooks/test-trace-grpc.js
index f91348cd3..1ae767d80 100644
--- a/test/hooks/test-trace-grpc.js
+++ b/test/hooks/test-trace-grpc.js
@@ -276,7 +276,7 @@ Object.keys(versions).forEach(function(version) {
             var trace = common.getMatchingSpan(predicate);
             assert(trace);
             assert.strictEqual(trace.labels.argument, '{"n":' + EMIT_ERROR + '}');
-            assert.strictEqual(trace.labels.error, 'Error: test');
+            assert(trace.labels.error.indexOf('Error: test') !== -1);
           };
           assertTraceProperties(grpcClientPredicate);
           assertTraceProperties(grpcServerPredicate);
@@ -293,7 +293,7 @@ Object.keys(versions).forEach(function(version) {
           var assertTraceProperties = function(predicate) {
             var trace = common.getMatchingSpan(predicate);
             assert(trace);
-            assert.strictEqual(trace.labels.error, 'Error: test');
+            assert(trace.labels.error.indexOf('Error: test') !== -1);
           };
           assertTraceProperties(grpcClientPredicate);
           assertTraceProperties(grpcServerPredicate);
@@ -313,7 +313,7 @@ Object.keys(versions).forEach(function(version) {
           var assertTraceProperties = function(predicate) {
             var trace = common.getMatchingSpan(predicate);
             assert(trace);
-            assert.strictEqual(trace.labels.error, 'Error: test');
+            assert(trace.labels.error.indexOf('Error: test') !== -1);
           };
           assertTraceProperties(grpcClientPredicate);
           assertTraceProperties(grpcServerPredicate);
@@ -333,7 +333,7 @@ Object.keys(versions).forEach(function(version) {
           var assertTraceProperties = function(predicate) {
             var trace = common.getMatchingSpan(predicate);
             assert(trace);
-            assert.strictEqual(trace.labels.error, 'Error: test');
+            assert(trace.labels.error.indexOf('Error: test') !== -1);
           };
           assertTraceProperties(grpcClientPredicate);
           assertTraceProperties(grpcServerPredicate);
diff --git a/test/test-trace-span.js b/test/test-trace-span.js
index c41a8816a..fa9757827 100644
--- a/test/test-trace-span.js
+++ b/test/test-trace-span.js
@@ -45,6 +45,12 @@ describe('TraceSpan', function() {
     assert.equal(span.labels.c, '5');
   });
 
+  it ('serializes object labels correctly', function() {
+    var span = new TraceSpan('name', 1, 0);
+    span.setLabel('a', [{i: 5}, {j: 6}]);
+    assert.equal(span.labels.a, '[ { i: 5 }, { j: 6 } ]');
+  });
+
   it('closes', function() {
     var span = new TraceSpan('name', 1, 0);
     assert.equal(span.endTime, '');