MockK calls actual method when using mockkConstructor

Question

I'm trying to mock the constructor of a class, and define some behaviour on the methods of the constructed object. I'm using mockk to do this, and following their instructions to get it setup. However, I'm finding that when I try to define the mock behaviour, mockk is invoking the actual underlying method in the class, which fails because there are things missing on the mock.

Here's a minimal example

class TestConstructed() {
    fun justThrows(): Int {
        throw NotImplementedError()
    }
}

class MinimalExample {
    @Test
    fun testMockConstructor() {
        mockkConstructor(TestConstructed::class)
        every { anyConstructed<TestConstructed>().justThrows() } returns 42

        val constructed = TestConstructed()

        assertThat(constructed.justThrows()).isEqualTo(42)
    }
}

In the case above the call to justThrows inside every throws an exception, so the test never passes. What I want is to be able to mock the call to justThrows without the exception being thrown.

I'm using MockK 1.13.10 and running with JUnit 5.10.0

Thoughts?