diff --git a/composer.json b/composer.json
index 1c5135f..4d3f1b4 100755
--- a/composer.json
+++ b/composer.json
@@ -18,11 +18,11 @@
         "ext-simplexml": "*",
         "composer/semver": "^1.4",
         "ocramius/package-versions": "^1.3",
-        "phpunit/phpunit": "^6.0 || ^7.0 || ^8.0 || ^9.0",
+        "phpunit/phpunit": "^7.5 || ^8.0 || ^9.0",
         "vimeo/psalm": "^3.6.2 || dev-master"
     },
     "require-dev": {
-        "codeception/base": "^2.5",
+        "codeception/codeception": "^4.0.3",
         "squizlabs/php_codesniffer": "^3.3.1",
         "weirdan/codeception-psalm-module": "^0.4.0"
     },
diff --git a/src/Plugin.php b/src/Plugin.php
index c34f272..cd3bd08 100755
--- a/src/Plugin.php
+++ b/src/Plugin.php
@@ -15,10 +15,7 @@ class Plugin implements PluginEntryPointInterface
     /** @return void */
     public function __invoke(RegistrationInterface $psalm, SimpleXMLElement $config = null)
     {
-        $psalm->addStubFile(__DIR__ . '/../stubs/Assert.phpstub');
-        if ($this->packageVersionIs('phpunit/phpunit', '>=', '7.5')) {
-            $psalm->addStubFile(__DIR__ . '/../stubs/Assert_75.phpstub');
-        }
+        $psalm->addStubFile(__DIR__ . '/../stubs/Assert_75.phpstub');
         $psalm->addStubFile(__DIR__ . '/../stubs/TestCase.phpstub');
         $psalm->addStubFile(__DIR__ . '/../stubs/MockBuilder.phpstub');
         $psalm->addStubFile(__DIR__ . '/../stubs/InvocationMocker.phpstub');
diff --git a/stubs/Assert.phpstub b/stubs/Assert.phpstub
deleted file mode 100644
index 88a86ef..0000000
--- a/stubs/Assert.phpstub
+++ /dev/null
@@ -1,118 +0,0 @@
-<?php
-
-namespace PHPUnit\Framework;
-
-abstract class Assert
-{
-    /**
-     * Asserts that a variable is of a given type.
-     *
-     * @param class-string $expected
-     * @param mixed  $actual
-     * @param string $message
-     *
-     * @template T
-     * @template-typeof T $expected
-     * @psalm-assert T $actual
-     */
-    public static function assertInstanceOf($expected, $actual, $message = '') {}
-
-    /**
-     * Asserts that a variable is of a given type.
-     *
-     * @param class-string $expected
-     * @param mixed  $actual
-     * @param string $message
-     *
-     * @template T
-     * @template-typeof T $expected
-     * @psalm-assert !T $actual
-     */
-    public static function assertNotInstanceOf($expected, $actual, $message = '') {}
-
-    /**
-     * Asserts that a condition is true.
-     *
-     * @param mixed  $condition
-     * @param string $message
-     *
-     * @throws AssertionFailedError
-     * @psalm-assert true $condition
-     */
-    public static function assertTrue($condition, $message = '') {}
-
-    /**
-     * Asserts that a condition is not true.
-     *
-     * @param mixed  $condition
-     * @param string $message
-     *
-     * @throws AssertionFailedError
-     * @psalm-assert !true $condition
-     */
-    public static function assertNotTrue($condition, $message = '') {}
-
-    /**
-     * Asserts that a condition is false.
-     *
-     * @param mixed  $condition
-     * @param string $message
-     *
-     * @throws AssertionFailedError
-     * @psalm-assert false $condition
-     */
-    public static function assertFalse($condition, $message = '') {}
-
-    /**
-     * Asserts that a condition is not false.
-     *
-     * @param mixed  $condition
-     * @param string $message
-     *
-     * @throws AssertionFailedError
-     * @psalm-assert !false $condition
-     */
-    public static function assertNotFalse($condition, $message = '') {}
-
-    /**
-     * Asserts that a variable is null.
-     *
-     * @param mixed  $actual
-     * @param string $message
-     * @psalm-assert null $actual
-     */
-    public static function assertNull($actual, $message = '') {}
-
-    /**
-     * Asserts that a variable is not null.
-     *
-     * @param mixed  $actual
-     * @param string $message
-     * @psalm-assert !null $actual
-     */
-    public static function assertNotNull($actual, $message = '') {}
-
-    /**
-     * Asserts that two variables are the same.
-     *
-     * @template T
-     * @param T      $expected
-     * @param mixed  $actual
-     * @param string $message
-     * @psalm-assert =T $actual
-     * @return void
-     */
-    public static function assertSame($expected, $actual, $message = '') {}
-
-    /**
-     * Asserts that two variables are not the same.
-     *
-     * @template T
-     * @param T      $expected
-     * @param mixed  $actual
-     * @param string $message
-     * @psalm-assert !=T $actual
-     * @return void
-     */
-    public static function assertNotSame($expected, $actual, $message = '') {}
-}
diff --git a/stubs/Assert_75.phpstub b/stubs/Assert_75.phpstub
index a69c05a..a318639 100644
--- a/stubs/Assert_75.phpstub
+++ b/stubs/Assert_75.phpstub
@@ -157,4 +157,115 @@ abstract class Assert
      */
     public static function assertIsNotIterable($actual, string $message = '') {}
 
+    /**
+     * Asserts that a variable is of a given type.
+     *
+     * @param class-string $expected
+     * @param mixed  $actual
+     * @param string $message
+     *
+     * @template T
+     * @template-typeof T $expected
+     * @psalm-assert T $actual
+     */
+    public static function assertInstanceOf($expected, $actual, $message = '') {}
+
+    /**
+     * Asserts that a variable is of a given type.
+     *
+     * @param class-string $expected
+     * @param mixed  $actual
+     * @param string $message
+     *
+     * @template T
+     * @template-typeof T $expected
+     * @psalm-assert !T $actual
+     */
+    public static function assertNotInstanceOf($expected, $actual, $message = '') {}
+
+    /**
+     * Asserts that a condition is true.
+     *
+     * @param mixed  $condition
+     * @param string $message
+     *
+     * @throws AssertionFailedError
+     * @psalm-assert true $condition
+     */
+    public static function assertTrue($condition, $message = '') {}
+
+    /**
+     * Asserts that a condition is not true.
+     *
+     * @param mixed  $condition
+     * @param string $message
+     *
+     * @throws AssertionFailedError
+     * @psalm-assert !true $condition
+     */
+    public static function assertNotTrue($condition, $message = '') {}
+
+    /**
+     * Asserts that a condition is false.
+     *
+     * @param mixed  $condition
+     * @param string $message
+     *
+     * @throws AssertionFailedError
+     * @psalm-assert false $condition
+     */
+    public static function assertFalse($condition, $message = '') {}
+
+    /**
+     * Asserts that a condition is not false.
+     *
+     * @param mixed  $condition
+     * @param string $message
+     *
+     * @throws AssertionFailedError
+     * @psalm-assert !false $condition
+     */
+    public static function assertNotFalse($condition, $message = '') {}
+
+    /**
+     * Asserts that a variable is null.
+     *
+     * @param mixed  $actual
+     * @param string $message
+     * @psalm-assert null $actual
+     */
+    public static function assertNull($actual, $message = '') {}
+
+    /**
+     * Asserts that a variable is not null.
+     *
+     * @param mixed  $actual
+     * @param string $message
+     * @psalm-assert !null $actual
+     */
+    public static function assertNotNull($actual, $message = '') {}
+
+    /**
+     * Asserts that two variables are the same.
+     *
+     * @template T
+     * @param T      $expected
+     * @param mixed  $actual
+     * @param string $message
+     * @psalm-assert =T $actual
+     * @return void
+     */
+    public static function assertSame($expected, $actual, $message = '') {}
+
+    /**
+     * Asserts that two variables are not the same.
+     *
+     * @template T
+     * @param T      $expected
+     * @param mixed  $actual
+     * @param string $message
+     * @psalm-assert !=T $actual
+     * @return void
+     */
+    public static function assertNotSame($expected, $actual, $message = '') {}
 }
diff --git a/tests/acceptance/Assert.feature b/tests/acceptance/Assert.feature
deleted file mode 100644
index ca3b0a8..0000000
--- a/tests/acceptance/Assert.feature
+++ /dev/null
@@ -1,42 +0,0 @@
-Feature: Assert
-  In order to use PHPUnit safely
-  As a Psalm user
-  I need Psalm to typecheck asserts
-
-  Background:
-    Given I have the following config
-      """
-      <?xml version="1.0"?>
-      <psalm>
-        <projectFiles><directory name="." /></projectFiles>
-        <plugins>
-          <pluginClass class="Psalm\PhpUnitPlugin\Plugin"/>
-        </plugins>
-      </psalm>
-      """
-    And I have the following code preamble
-      """
-      <?php
-      namespace NS;
-      use PHPUnit\Framework\Assert;
-
-      """
-
-  Scenario: Assert::assertInstanceOf()
-    Given I have the following code
-      """
-      function f(): \Exception {
-        return rand(0,1) ? new \RuntimeException : new \InvalidArgumentException;
-      }
-
-      /**
-       * @return void
-       */
-      function acceptsRuntimeException(\RuntimeException $_e) {}
-
-      $e = f();
-      Assert::assertInstanceOf(\RuntimeException::class, $e);
-      acceptsRuntimeException($e);
-      """
-    When I run Psalm
-    Then I see no errors
diff --git a/tests/acceptance/Assert75.feature b/tests/acceptance/Assert75.feature
index aed8fb0..03d209e 100644
--- a/tests/acceptance/Assert75.feature
+++ b/tests/acceptance/Assert75.feature
@@ -29,6 +29,25 @@ Feature: Assert (PHPUnit 7.5+)
       """
     And I have PHPUnit newer than "7.4.99999" (because of "new features in 7.5")
 
+  Scenario: Assert::assertInstanceOf()
+    Given I have the following code
+      """
+      function f(): \Exception {
+        return rand(0,1) ? new \RuntimeException : new \InvalidArgumentException;
+      }
+
+      /**
+       * @return void
+       */
+      function acceptsRuntimeException(\RuntimeException $_e) {}
+
+      $e = f();
+      Assert::assertInstanceOf(\RuntimeException::class, $e);
+      acceptsRuntimeException($e);
+      """
+    When I run Psalm
+    Then I see no errors
+
   Scenario: Assert::assertIsArray()
     Given I have the following code
       """
diff --git a/tests/acceptance/TestCase.feature b/tests/acceptance/TestCase.feature
index 6428f92..1b76693 100644
--- a/tests/acceptance/TestCase.feature
+++ b/tests/acceptance/TestCase.feature
@@ -69,7 +69,7 @@ Feature: TestCase
         private $i;
 
         /** @return void */
-        public function setUp() {
+        public function setUp(): void {
           $this->i = $this->prophesize(I::class);
         }
 
@@ -712,7 +712,7 @@ Feature: TestCase
         private $i;
 
         /** @return void */
-        public function setUp() {
+        public function setUp(): void {
           $this->i = $this->prophesize(I::class);
         }
 
@@ -739,7 +739,7 @@ Feature: TestCase
         protected $i;
 
         /** @return void */
-        public function setUp() {
+        public function setUp(): void {
           $this->i = $this->prophesize(I::class);
         }
       }