diff --git a/CHANGELOG.md b/CHANGELOG.md
index b69d8b8..b380efb 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -7,6 +7,8 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## 0.1.1 Under development
 
+- fix(event): skip `InstrumentationGuard` trace frames on Windows by joining the skip path with `DIRECTORY_SEPARATOR`.
+
 ## 0.1.0 October 16, 2026
 
 - feat: initial development release.
diff --git a/composer.json b/composer.json
index fda4104..a67c682 100644
--- a/composer.json
+++ b/composer.json
@@ -73,7 +73,7 @@
         "mutation-static": [
             "Composer\\Config::disableProcessTimeout",
             "./vendor/bin/phpstan clear-result-cache",
-            "php -d memory_limit=-1 vendor/bin/infection --threads=4 --ignore-msi-with-no-mutations --min-msi=100 --min-covered-msi=100 --static-analysis-tool=phpstan --static-analysis-tool-options='--memory-limit=-1'"
+            "php -d memory_limit=-1 vendor/bin/infection --initial-tests-php-options='-d memory_limit=-1' --test-framework-extra-args='-d memory_limit=-1' --threads=4 --ignore-msi-with-no-mutations --min-msi=100 --min-covered-msi=100 --static-analysis-tool=phpstan --static-analysis-tool-options='--memory-limit=-1'"
         ],
         "rector": "./vendor/bin/rector process",
         "static": "./vendor/bin/phpstan --memory-limit=-1",
diff --git a/src/Panel/Event/EventCapture.php b/src/Panel/Event/EventCapture.php
index e24d057..6c339d3 100644
--- a/src/Panel/Event/EventCapture.php
+++ b/src/Panel/Event/EventCapture.php
@@ -58,7 +58,9 @@ public static function trace(array $frames, int $limit, array $skipFiles = []):
         $result = [];
         $skipFiles[] = __FILE__;
 
-        $skipFiles[] = dirname(__DIR__, 2) . '/Instrumentation/InstrumentationGuard.php';
+        $skipFiles[] = dirname(__DIR__, 2)
+            . DIRECTORY_SEPARATOR . 'Instrumentation'
+            . DIRECTORY_SEPARATOR . 'InstrumentationGuard.php';
 
         foreach ($frames as $frame) {
             if (count($result) >= min(16, $limit)) {
diff --git a/tests/Panel/Event/EventInspectionTest.php b/tests/Panel/Event/EventInspectionTest.php
index 286eb7d..092bfcb 100644
--- a/tests/Panel/Event/EventInspectionTest.php
+++ b/tests/Panel/Event/EventInspectionTest.php
@@ -5,11 +5,13 @@
 namespace PHPForge\Debug\Tests\Panel\Event;
 
 use Closure;
+use PHPForge\Debug\Instrumentation\InstrumentationGuard;
 use PHPForge\Debug\Panel\Event\{EventCapture, EventInspection, EventInspectorRenderer, EventRow, EventSequence, EventSnapshot};
 use PHPForge\Debug\Storage\HydrationException;
 use PHPForge\Debug\Tests\Provider\EventInspectionProvider;
 use PHPUnit\Framework\Attributes\{DataProviderExternal, Group};
 use PHPUnit\Framework\TestCase;
+use ReflectionClass;
 
 use function array_replace;
 use function strlen;
@@ -614,6 +616,26 @@ public function testTraceNeverRetainsArgumentsOrObjects(): void
         );
     }
 
+    public function testTraceSkipsInstrumentationGuardFramesWithNativeSeparators(): void
+    {
+        $frames = [
+            [
+                'file' => (string) (new ReflectionClass(InstrumentationGuard::class))->getFileName(),
+                'line' => 36,
+            ],
+            [
+                'file' => '/app/event.php',
+                'line' => 42,
+            ],
+        ];
+
+        self::assertSame(
+            ['/app/event.php:42'],
+            EventCapture::trace($frames, 16),
+            'Instrumentation guard frames must be skipped on every platform.',
+        );
+    }
+
     private static function row(float $time): EventRow
     {
         return new EventRow($time, 'render', 'ViewEvent', '0', 'View');