diff --git a/src/Concerns/Testable.php b/src/Concerns/Testable.php
index 82a0c166..a973d132 100644
--- a/src/Concerns/Testable.php
+++ b/src/Concerns/Testable.php
@@ -87,7 +87,7 @@ trait Testable
      */
     public function __addBeforeAll(?Closure $hook): void
     {
-        if ($hook === null) {
+        if (! $hook instanceof \Closure) {
             return;
         }
 
@@ -101,7 +101,7 @@ trait Testable
      */
     public function __addAfterAll(?Closure $hook): void
     {
-        if ($hook === null) {
+        if (! $hook instanceof \Closure) {
             return;
         }
 
@@ -131,7 +131,7 @@ trait Testable
      */
     private function __addHook(string $property, ?Closure $hook): void
     {
-        if ($hook === null) {
+        if (! $hook instanceof \Closure) {
             return;
         }
 
diff --git a/src/Factories/TestCaseFactory.php b/src/Factories/TestCaseFactory.php
index 50043648..0b5b66f4 100644
--- a/src/Factories/TestCaseFactory.php
+++ b/src/Factories/TestCaseFactory.php
@@ -217,7 +217,7 @@ final class TestCaseFactory
         }
 
         if (! $method->receivesArguments()) {
-            if ($method->closure === null) {
+            if (! $method->closure instanceof \Closure) {
                 throw ShouldNotHappen::fromMessage('The test closure may not be empty.');
             }
 
diff --git a/src/Functions.php b/src/Functions.php
index 42d8c964..ede5141c 100644
--- a/src/Functions.php
+++ b/src/Functions.php
@@ -92,7 +92,7 @@ if (! function_exists('test')) {
      */
     function test(string $description = null, Closure $closure = null): HigherOrderTapProxy|TestCall
     {
-        if ($description === null && TestSuite::getInstance()->test !== null) {
+        if ($description === null && TestSuite::getInstance()->test instanceof \PHPUnit\Framework\TestCase) {
             return new HigherOrderTapProxy(TestSuite::getInstance()->test);
         }
 
diff --git a/src/Logging/TeamCity/TeamCityLogger.php b/src/Logging/TeamCity/TeamCityLogger.php
index af0ef5c0..eadfada8 100644
--- a/src/Logging/TeamCity/TeamCityLogger.php
+++ b/src/Logging/TeamCity/TeamCityLogger.php
@@ -180,7 +180,7 @@ final class TeamCityLogger
 
     public function testFinished(Finished $event): void
     {
-        if ($this->time === null) {
+        if (! $this->time instanceof \PHPUnit\Event\Telemetry\HRTime) {
             throw ShouldNotHappen::fromMessage('Start time has not been set.');
         }
 
diff --git a/src/Mixins/Expectation.php b/src/Mixins/Expectation.php
index ad95ea98..3bfcdadd 100644
--- a/src/Mixins/Expectation.php
+++ b/src/Mixins/Expectation.php
@@ -900,7 +900,7 @@ final class Expectation
      */
     private function export(mixed $value): string
     {
-        if ($this->exporter === null) {
+        if (! $this->exporter instanceof \Pest\Support\Exporter) {
             $this->exporter = Exporter::default();
         }
 
diff --git a/src/Support/Container.php b/src/Support/Container.php
index af15d003..b780fd72 100644
--- a/src/Support/Container.php
+++ b/src/Support/Container.php
@@ -25,7 +25,7 @@ final class Container
      */
     public static function getInstance(): self
     {
-        if (self::$instance === null) {
+        if (! self::$instance instanceof \Pest\Support\Container) {
             self::$instance = new self();
         }
 
@@ -72,7 +72,7 @@ final class Container
         if ($reflectionClass->isInstantiable()) {
             $constructor = $reflectionClass->getConstructor();
 
-            if ($constructor !== null) {
+            if ($constructor instanceof \ReflectionMethod) {
                 $params = array_map(
                     function (ReflectionParameter $param) use ($id): object|string {
                         $candidate = Reflection::getParameterClassName($param);
@@ -80,7 +80,7 @@ final class Container
                         if ($candidate === null) {
                             $type = $param->getType();
                             /* @phpstan-ignore-next-line */
-                            if ($type !== null && $type->isBuiltin()) {
+                            if ($type instanceof \ReflectionType && $type->isBuiltin()) {
                                 $candidate = $param->getName();
                             } else {
                                 throw ShouldNotHappen::fromMessage(sprintf('The type of `$%s` in `%s` cannot be determined.', $id, $param->getName()));