diff --git a/phpstan.neon.dist b/phpstan.neon.dist
index 79a6024..3621d3d 100644
--- a/phpstan.neon.dist
+++ b/phpstan.neon.dist
@@ -22,11 +22,6 @@ parameters:
 	ignoreErrors:
 		# Level 0
 		# This is part of the functionality of this library. Ignore.
-		-
-			message: '`^Call to an undefined static method Yoast\\PHPUnitPolyfills\\TestCases\\[X]?TestCase::assertInternalType\(\)\.$`'
-			count: 2
-			path: src/Polyfills/AssertIsList.php
-
 		-
 			message: '`^Call to an undefined method Yoast\\PHPUnitPolyfills\\TestCases\\[X]?TestCase::expectExceptionMessageRegExp\(\)\.$`'
 			count: 2
@@ -42,10 +37,6 @@ parameters:
 			message: "`^Call to function method_exists\\(\\) with 'PHPUnit\\W+Framework\\W+TestCase' and 'expectDeprecationMe[^']+' will always evaluate to true\\.$`"
 			count: 4
 			path: src/Polyfills/ExpectUserDeprecation.php
-		-
-			message: "`^Call to function method_exists\\(\\) with 'PHPUnit\\W+Framework\\W+Assert' and 'assertIsArray' will always evaluate to true\\.$`"
-			count: 2
-			path: src/Polyfills/AssertIsList.php
 
 		-
 			message: '`^Call to static method PHPUnit\\Framework\\Assert::assertIsArray\(\) with mixed and mixed will always evaluate to false\.$`'
diff --git a/src/Polyfills/AssertContainsOnly.php b/src/Polyfills/AssertContainsOnly.php
index b8478ed..8208ed7 100644
--- a/src/Polyfills/AssertContainsOnly.php
+++ b/src/Polyfills/AssertContainsOnly.php
@@ -5,8 +5,6 @@
 use PHPUnit\SebastianBergmann\Exporter\Exporter as Exporter_In_Phar_Old;
 use PHPUnitPHAR\SebastianBergmann\Exporter\Exporter as Exporter_In_Phar;
 use SebastianBergmann\Exporter\Exporter;
-use Traversable;
-use Yoast\PHPUnitPolyfills\Autoload;
 use Yoast\PHPUnitPolyfills\Helpers\ResourceHelper;
 
 /**
@@ -164,87 +162,25 @@ final public static function assertContainsNotOnlyInt( $haystack, string $messag
 	/**
 	 * Asserts that $haystack only contains values of type iterable.
 	 *
-	 * {@internal Support for `iterable` was only added to the `IsType` constraint
-	 * in PHPUnit 7.1.0, so this polyfill can't use a direct fall-through to the PHPUnit native
-	 * functionality until the minimum supported PHPUnit version of this library would be PHPUnit 7.1.0.}
-	 *
-	 * @link https://github.com/sebastianbergmann/phpunit/pull/3035 PR which added support for `is_iterable`.
-	 *
 	 * @param iterable<mixed> $haystack The variable to test.
 	 * @param string          $message  Optional failure message to display.
 	 *
 	 * @return void
 	 */
 	final public static function assertContainsOnlyIterable( $haystack, string $message = '' ) {
-		if ( \version_compare( Autoload::getPHPUnitVersion(), '7.1.0', '>=' ) ) {
-			// PHPUnit >= 7.1.0.
-			static::assertContainsOnly( 'iterable', $haystack, true, $message );
-		}
-		else {
-			// PHPUnit 6.x/7.0.0.
-			$exporter = self::getPHPUnitExporterObjectForContainsOnly();
-			$msg      = \sprintf( 'Failed asserting that %s contains only values of type "iterable".', $exporter->export( $haystack ) );
-
-			if ( $message !== '' ) {
-				$msg = $message . \PHP_EOL . $msg;
-			}
-
-			$hasOnlyIterable = true;
-			foreach ( $haystack as $value ) {
-				if ( \is_array( $value ) || $value instanceof Traversable ) {
-					continue;
-				}
-
-				$hasOnlyIterable = false;
-				break;
-			}
-
-			static::assertTrue( $hasOnlyIterable, $msg );
-		}
+		static::assertContainsOnly( 'iterable', $haystack, true, $message );
 	}
 
 	/**
 	 * Asserts that $haystack does not only contain values of type iterable.
 	 *
-	 * {@internal Support for `iterable` was only added to the `IsType` constraint
-	 * in PHPUnit 7.1.0, so this polyfill can't use a direct fall-through to the PHPUnit native
-	 * functionality until the minimum supported PHPUnit version of this library would be PHPUnit 7.1.0.}
-	 *
-	 * @link https://github.com/sebastianbergmann/phpunit/pull/3035 PR which added support for `is_iterable`.
-	 *
 	 * @param iterable<mixed> $haystack The variable to test.
 	 * @param string          $message  Optional failure message to display.
 	 *
 	 * @return void
 	 */
 	final public static function assertContainsNotOnlyIterable( $haystack, string $message = '' ) {
-		if ( \function_exists( 'is_iterable' ) === true
-			&& \version_compare( Autoload::getPHPUnitVersion(), '7.1.0', '>=' )
-		) {
-			// PHP >= 7.1 with PHPUnit >= 7.1.0.
-			static::assertNotContainsOnly( 'iterable', $haystack, true, $message );
-		}
-		else {
-			// PHP < 7.1 or PHPUnit 6.x/7.0.0.
-			$exporter = self::getPHPUnitExporterObjectForContainsOnly();
-			$msg      = \sprintf( 'Failed asserting that %s does not contain only values of type "iterable".', $exporter->export( $haystack ) );
-
-			if ( $message !== '' ) {
-				$msg = $message . \PHP_EOL . $msg;
-			}
-
-			$hasOnlyIterable = true;
-			foreach ( $haystack as $value ) {
-				if ( \is_array( $value ) || $value instanceof Traversable ) {
-					continue;
-				}
-
-				$hasOnlyIterable = false;
-				break;
-			}
-
-			static::assertFalse( $hasOnlyIterable, $msg );
-		}
+		static::assertNotContainsOnly( 'iterable', $haystack, true, $message );
 	}
 
 	/**
diff --git a/src/Polyfills/AssertIsList.php b/src/Polyfills/AssertIsList.php
index f1e55e8..89824e0 100644
--- a/src/Polyfills/AssertIsList.php
+++ b/src/Polyfills/AssertIsList.php
@@ -2,7 +2,6 @@
 
 namespace Yoast\PHPUnitPolyfills\Polyfills;
 
-use PHPUnit\Framework\Assert;
 use ReflectionObject;
 
 /**
@@ -31,12 +30,7 @@ final public static function assertIsList( $array, $message = '' ) {
 		}
 
 		if ( \is_array( $array ) === false ) {
-			if ( \method_exists( Assert::class, 'assertIsArray' ) ) {
-				static::assertIsArray( $array, $msg );
-				return;
-			}
-
-			static::assertInternalType( 'array', $array, $msg );
+			static::assertIsArray( $array, $msg );
 			return;
 		}