diff --git a/Makefile b/Makefile
index 63591f8b..161e5865 100644
--- a/Makefile
+++ b/Makefile
@@ -36,7 +36,7 @@ csfix: ## Run phpcs fixer
 	docker compose run php$(PHP_VERSION) vendor/bin/phpcbf
 
 box: ## Compile /build/composer-unused.phar
-	docker compose run php$(PHP_VERSION) php box.phar compile
+	docker compose run php$(PHP_VERSION) php .phive/box.phar compile
 
 ssh: ## SSH into container
 	docker compose run php$(PHP_VERSION) /bin/sh
diff --git a/phpstan.neon b/phpstan.neon
index ac12398b..dd3ff797 100644
--- a/phpstan.neon
+++ b/phpstan.neon
@@ -6,7 +6,7 @@ parameters:
         - phpunit.bootstrap.php
     excludes_analyse:
         - %currentWorkingDirectory%/tests/assets
-    level: max
+    level: 8
     inferPrivatePropertyTypeFromConstructor: true
     paths:
         - bin/
diff --git a/src/Symbol/ConsumedSymbolLoaderBuilder.php b/src/Symbol/ConsumedSymbolLoaderBuilder.php
index 3acccb9b..4bcb13d8 100644
--- a/src/Symbol/ConsumedSymbolLoaderBuilder.php
+++ b/src/Symbol/ConsumedSymbolLoaderBuilder.php
@@ -8,6 +8,11 @@
 use ComposerUnused\SymbolParser\Parser\PHP\AutoloadType;
 use ComposerUnused\SymbolParser\Parser\PHP\ConsumedSymbolCollector;
 use ComposerUnused\SymbolParser\Parser\PHP\Strategy\ClassConstStrategy;
+use ComposerUnused\SymbolParser\Parser\PHP\Strategy\ConstStrategy;
+use ComposerUnused\SymbolParser\Parser\PHP\Strategy\ExtendsParseStrategy;
+use ComposerUnused\SymbolParser\Parser\PHP\Strategy\FunctionInvocationStrategy;
+use ComposerUnused\SymbolParser\Parser\PHP\Strategy\ImplementsParseStrategy;
+use ComposerUnused\SymbolParser\Parser\PHP\Strategy\InstanceofStrategy;
 use ComposerUnused\SymbolParser\Parser\PHP\Strategy\NewStrategy;
 use ComposerUnused\SymbolParser\Parser\PHP\Strategy\StaticStrategy;
 use ComposerUnused\SymbolParser\Parser\PHP\Strategy\UsedExtensionSymbolStrategy;
@@ -27,15 +32,20 @@ public function build(): SymbolLoaderInterface
     {
         $usedSymbolCollector = new ConsumedSymbolCollector(
             [
+                new ClassConstStrategy(),
+                new ConstStrategy(),
+                new ExtendsParseStrategy(),
+                new FunctionInvocationStrategy(),
+                new ImplementsParseStrategy(),
+                new InstanceofStrategy(),
                 new NewStrategy(),
                 new StaticStrategy(),
-                new UseStrategy(),
-                new ClassConstStrategy(),
                 new UsedExtensionSymbolStrategy(
                     get_loaded_extensions(),
                     // TODO logger
                     new NullLogger()
-                )
+                ),
+                new UseStrategy(),
             ]
         );
 
diff --git a/tests/Integration/UnusedCommandTest.php b/tests/Integration/UnusedCommandTest.php
index 7a7047bc..22a00716 100644
--- a/tests/Integration/UnusedCommandTest.php
+++ b/tests/Integration/UnusedCommandTest.php
@@ -113,4 +113,17 @@ public function itShouldNotReportPatternExcludedPackages(): void
         self::assertStringContainsString('dummy/test-package', $commandTester->getDisplay());
         self::assertStringContainsString('Found 0 used, 1 unused and 0 ignored packages', $commandTester->getDisplay());
     }
+
+    /**
+     * @test
+     */
+    public function itShouldNotReportFileDependencyWithFunctionGuard(): void
+    {
+        chdir(__DIR__ . '/../assets/TestProjects/FileDependencyFunctionWithGuard');
+        $commandTester = new CommandTester($this->container->get(UnusedCommand::class));
+        $exitCode = $commandTester->execute([]);
+
+        self::assertSame(0, $exitCode);
+        self::assertStringContainsString('Found 1 used, 0 unused and 0 ignored packages', $commandTester->getDisplay());
+    }
 }
diff --git a/tests/assets/TestProjects/FileDependencyFunctionWithGuard/composer.json b/tests/assets/TestProjects/FileDependencyFunctionWithGuard/composer.json
new file mode 100644
index 00000000..29232cfd
--- /dev/null
+++ b/tests/assets/TestProjects/FileDependencyFunctionWithGuard/composer.json
@@ -0,0 +1,16 @@
+{
+  "name": "foo/bar",
+  "description": "foobar",
+  "type": "library",
+  "minimum-stability": "stable",
+  "require": {
+      "test/file-dependency": "*"
+  },
+  "autoload": {
+    "psr-4": {
+      "FileDependencyFunctionWithGuard\\": "src/"
+    }
+  },
+  "require-dev": {
+  }
+}
diff --git a/tests/assets/TestProjects/FileDependencyFunctionWithGuard/src/TestClass.php b/tests/assets/TestProjects/FileDependencyFunctionWithGuard/src/TestClass.php
new file mode 100644
index 00000000..3a6f0d8d
--- /dev/null
+++ b/tests/assets/TestProjects/FileDependencyFunctionWithGuard/src/TestClass.php
@@ -0,0 +1,13 @@
+<?php
+
+declare(strict_types=1);
+
+namespace FileDependencyFunctionWithGuard;
+
+class TestClass
+{
+    public function testMethod(): void
+    {
+        $b = testfunction2();
+    }
+}
diff --git a/tests/assets/TestProjects/FileDependencyFunctionWithGuard/vendor/composer/installed.json b/tests/assets/TestProjects/FileDependencyFunctionWithGuard/vendor/composer/installed.json
new file mode 100644
index 00000000..e7181621
--- /dev/null
+++ b/tests/assets/TestProjects/FileDependencyFunctionWithGuard/vendor/composer/installed.json
@@ -0,0 +1,17 @@
+[
+    {
+        "name": "test/file-dependency",
+        "type": "library",
+        "version": "1.0",
+        "description": "test dependency",
+        "autoload": {
+            "files": [
+                "src/file.php"
+            ]
+        },
+        "require": {
+        },
+        "require-dev": {
+        }
+    }
+]
diff --git a/tests/assets/TestProjects/FileDependencyFunctionWithGuard/vendor/test/file-dependency/composer.json b/tests/assets/TestProjects/FileDependencyFunctionWithGuard/vendor/test/file-dependency/composer.json
new file mode 100644
index 00000000..9bc27ef2
--- /dev/null
+++ b/tests/assets/TestProjects/FileDependencyFunctionWithGuard/vendor/test/file-dependency/composer.json
@@ -0,0 +1,14 @@
+{
+    "name": "test/file-dependency",
+    "type": "library",
+    "description": "test dependency",
+    "autoload": {
+        "files": [
+            "src/file.php"
+        ]
+    },
+    "require": {
+    },
+    "require-dev": {
+    }
+}
diff --git a/tests/assets/TestProjects/FileDependencyFunctionWithGuard/vendor/test/file-dependency/src/file.php b/tests/assets/TestProjects/FileDependencyFunctionWithGuard/vendor/test/file-dependency/src/file.php
new file mode 100644
index 00000000..ad7c3044
--- /dev/null
+++ b/tests/assets/TestProjects/FileDependencyFunctionWithGuard/vendor/test/file-dependency/src/file.php
@@ -0,0 +1,7 @@
+<?php
+
+declare(strict_types=1);
+
+if (!function_exists('testfunction2')) {
+    function testfunction2() {}
+}