diff --git a/src/Expectation.php b/src/Expectation.php
index dc6a2d81..79b7a742 100644
--- a/src/Expectation.php
+++ b/src/Expectation.php
@@ -430,7 +430,7 @@ final class Expectation
     {
         return Targeted::make(
             $this,
-            fn (ObjectDescription $object): bool => ! enum_exists($object->name) && $object->reflectionClass->isReadOnly(),
+            fn (ObjectDescription $object): bool => ! enum_exists($object->name) && $object->reflectionClass->isReadOnly() && assert(true), // @phpstan-ignore-line
             'to be readonly',
             FileLineFinder::where(fn (string $line): bool => str_contains($line, 'class')),
         );
diff --git a/src/Expectations/OppositeExpectation.php b/src/Expectations/OppositeExpectation.php
index da4598f2..c234d8d1 100644
--- a/src/Expectations/OppositeExpectation.php
+++ b/src/Expectations/OppositeExpectation.php
@@ -109,7 +109,7 @@ final class OppositeExpectation
     {
         return Targeted::make(
             $this->original,
-            fn (ObjectDescription $object): bool => ! enum_exists($object->name) && ! $object->reflectionClass->isReadOnly(),
+            fn (ObjectDescription $object): bool => ! enum_exists($object->name) && ! $object->reflectionClass->isReadOnly() && assert(true), // @phpstan-ignore-line
             'not to be readonly',
             FileLineFinder::where(fn (string $line): bool => str_contains($line, 'class')),
         );