PowerMock mockStatic didn't catch mocked static void method call

I try to mock a static void method with PowerMock over Mockito, but it doesn't work so well.

My sample code:

BlackTempleTest.java

package com;

import org.junit.Assert;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.mockito.invocation.InvocationOnMock;
import org.mockito.stubbing.Answer;
import org.powermock.api.mockito.PowerMockito;
import org.powermock.core.classloader.annotations.PrepareForTest;
import org.powermock.modules.junit4.PowerMockRunner;

import com.BlackTempleTest.Illidan;

@RunWith(PowerMockRunner.class)
@PrepareForTest({ Illidan.class, EvilBrother.class })
public class BlackTempleTest {

    Answer<Object> defaultAnswer = new Answer<Object>() {
        @Override
        public Object answer(InvocationOnMock invocation) throws Throwable {
            System.out.println("Haha!");
            return null;
        }
    };

    @Test(expected = AssertionError.class)
    public void testIllidanFight() throws Exception {
        Illidan.startFight();
    }

    @Test
    public void testCheatOnIllidanFight() throws Exception {
        PowerMockito.mockStatic(Illidan.class, defaultAnswer);

        Illidan.startFight();
    }

    @Test(expected = AssertionError.class)
    public void testEvilBrotherFight() throws Exception {
        EvilBrother.startFight();
    }

    // dont work
    @Test
    public void testCheatOnEvilBrotherFight() throws Exception {
        PowerMockito.mockStatic(EvilBrother.class, defaultAnswer);

        EvilBrother.startFight();
    }

    static class Illidan {
        static void startFight() {
            Assert.fail("You are not prepared!");
        }
    }
}

EvilBrother.java

package com;

import com.BlackTempleTest.Illidan;

public class EvilBrother extends Illidan {

}

My problem is, that the nested class is mocked as expected with a combination of @PrepareForTest and PowerMockito.mockStatic, but if the class is in its own class file, these statements don't work.

How can a fix this test?