diff --git a/vlib/v/checker/check_types.v b/vlib/v/checker/check_types.v
index 43826c4ff4..ecd9d0b281 100644
--- a/vlib/v/checker/check_types.v
+++ b/vlib/v/checker/check_types.v
@@ -140,12 +140,12 @@ pub fn (mut c Checker) check_basic(got ast.Type, expected ast.Type) bool {
 		return true
 	}
 	// allow `return 0` in a function with `?int` return type
-	expected_nonopt := expected.clear_flag(.optional)
-	if got == ast.int_literal_type && expected_nonopt.is_int() {
+	expected_nonflagged := expected.clear_flags()
+	if got == ast.int_literal_type && expected_nonflagged.is_int() {
 		return true
 	}
 	// allow `return 0` in a function with `?f32` return type
-	if got == ast.float_literal_type && expected_nonopt.is_float() {
+	if got == ast.float_literal_type && expected_nonflagged.is_float() {
 		return true
 	}
 	return false