diff --git a/CHANGES b/CHANGES
index ec9d81f..df11509 100644
--- a/CHANGES
+++ b/CHANGES
@@ -1,5 +1,6 @@
-1.3.1 (TBD):
-- Support finer granularity timeouts and milliseconds granularity
+1.4.0 (TBD):
+- Add support for a custom tracer for client methods.
+- Support finer granularity timeouts and milliseconds granularity.
 
 1.3.0 (Nov 10, 2023):
 - Added in-memory evaluation cache for the duration of a request.
diff --git a/examples/tracer.php b/examples/tracer.php
index fc0cd2c..877eda7 100644
--- a/examples/tracer.php
+++ b/examples/tracer.php
@@ -3,24 +3,24 @@
 require_once '../vendor/autoload.php';
 
 use \SplitIO\ThinSdk\Factory;
-use \SplitIO\ThinSdk\Utils\Tracer;
-use \SplitIO\ThinSdk\Utils\TracerHook;
+use \SplitIO\ThinSdk\Utils\Tracing\Tracer;
+use \SplitIO\ThinSdk\Utils\Tracing\TracerHook;
 
 class CustomTracer implements TracerHook
 {
 
     private $events = [];
 
-    public function on(int $method, int $event, ?array $arguments)
+    public function on(array $event)
     {
         // assume we only care about getTreatment() calls...
-        if ($method != Tracer::METHOD_GET_TREATMENT) {
+        if ($event['method'] != Tracer::METHOD_GET_TREATMENT) {
             return;
         }
 
-        switch ($event) {
+        switch ($event['event']) {
             case Tracer::EVENT_START:
-                array_push($this->events, "start (" . json_encode($arguments) . ") -- " . microtime(true));
+                array_push($this->events, "start (" . json_encode($event['arguments']) . ") -- " . microtime(true));
                 break;
             case Tracer::EVENT_RPC_START:
                 array_push($this->events, "about to send rpc -- " . microtime(true));
@@ -54,7 +54,7 @@ public function getEvents(): array
         'level' => \Psr\Log\LogLevel::INFO,
     ],
     'utils' => [
-        '__tracer' => [
+        'tracer' => [
             'hook' => $ct,
             'forwardArgs' => true,
         ]
diff --git a/src/Config/Utils.php b/src/Config/Utils.php
index d575830..89be7e0 100644
--- a/src/Config/Utils.php
+++ b/src/Config/Utils.php
@@ -39,7 +39,7 @@ public static function fromArray(array $config): Utils
         return new Utils(
             $config['impressionListener'] ?? $d->impressionListener(),
             EvaluationCache::fromArray($config['evaluationCache'] ?? []),
-            Tracer::fromArray($config['__tracer'] ?? []),
+            Tracer::fromArray($config['tracer'] ?? []),
         );
     }
 
diff --git a/tests/Config/UtilsTest.php b/tests/Config/UtilsTest.php
index b033d6a..674cfd1 100644
--- a/tests/Config/UtilsTest.php
+++ b/tests/Config/UtilsTest.php
@@ -35,7 +35,7 @@ public function testConfigParsing()
                 'maxSize' => 1234,
                 'customHash' => $ihMock,
             ],
-            '__tracer' => [
+            'tracer' => [
                 'hook' => $tMock,
                 'forwardArgs' => true,
             ],