diff --git a/kunit/src/main/kotlin/Test.kt b/kunit/src/main/kotlin/Test.kt
index 30fbd211eca..e094a0066fc 100644
--- a/kunit/src/main/kotlin/Test.kt
+++ b/kunit/src/main/kotlin/Test.kt
@@ -65,7 +65,7 @@ inline fun <T> expect(expected: T, message: String, block: ()-> T) {
 }
 
 /** Asserts that given function block fails by throwing an exception */
-fun fails(block: ()-> Any): Exception? {
+fun fails(block: ()-> Unit): Exception? {
     try {
         block()
         Assert.fail("Expected an exception to be thrown")