diff --git a/vlib/v/fmt/tests/fntype_mut_args_with_optional_keep.vv b/vlib/v/fmt/tests/fntype_mut_args_with_optional_keep.vv
new file mode 100644
index 0000000000..efb2685d03
--- /dev/null
+++ b/vlib/v/fmt/tests/fntype_mut_args_with_optional_keep.vv
@@ -0,0 +1 @@
+pub type SocketMessageFn = fn (mut c Client, msg &Message) ?
diff --git a/vlib/v/fmt/tests/fntype_return_optional_input.vv b/vlib/v/fmt/tests/fntype_return_optional_input.vv
deleted file mode 100644
index 58bac90ca5..0000000000
--- a/vlib/v/fmt/tests/fntype_return_optional_input.vv
+++ /dev/null
@@ -1,3 +0,0 @@
-type Foo = fn (a int)?
-
-type Foo2 = fn (num int)?int
diff --git a/vlib/v/fmt/tests/fntype_return_optional_expected.vv b/vlib/v/fmt/tests/fntype_return_optional_keep.vv
similarity index 100%
rename from vlib/v/fmt/tests/fntype_return_optional_expected.vv
rename to vlib/v/fmt/tests/fntype_return_optional_keep.vv