diff --git a/library/aik099/PHPUnit/TestSuite/AbstractTestSuite.php b/library/aik099/PHPUnit/TestSuite/AbstractTestSuite.php
index 3dab462..b4c0d63 100644
--- a/library/aik099/PHPUnit/TestSuite/AbstractTestSuite.php
+++ b/library/aik099/PHPUnit/TestSuite/AbstractTestSuite.php
@@ -47,13 +47,13 @@ public function addTestMethods($class_name)
 
 		if ( \method_exists($this, 'isTestMethod') ) {
 			// PHPUnit < 8.0 is calling "isTestMethod" inside "TestSuite::addTestMethod".
-			foreach ( $class->getMethods(\ReflectionMethod::IS_PUBLIC) as $method ) {
+			foreach ( $this->getTestMethods($class) as $method ) {
 				$this->addTestMethod($class, $method);
 			}
 		}
 		else {
 			// PHPUnit >= 8.0 is calling "TestUtil::isTestMethod" outside of "TestSuite::addTestMethod".
-			foreach ( $class->getMethods(\ReflectionMethod::IS_PUBLIC) as $method ) {
+			foreach ( $this->getTestMethods($class) as $method ) {
 				if ( TestUtil::isTestMethod($method) ) {
 					$this->addTestMethod($class, $method);
 				}
@@ -63,6 +63,22 @@ public function addTestMethods($class_name)
 		return $this;
 	}
 
+	/**
+	 * Returns test methods.
+	 *
+	 * @param \ReflectionClass $class Reflection class.
+	 *
+	 * @return \ReflectionMethod[]
+	 */
+	protected function getTestMethods(\ReflectionClass $class)
+	{
+		$ret = $class->getMethods(\ReflectionMethod::IS_PUBLIC);
+
+		return \array_filter($ret, function (\ReflectionMethod $method) {
+			return !$method->isStatic();
+		});
+	}
+
 	/**
 	 * Sets session strategy manager recursively to all tests.
 	 *