diff --git a/checker/checker.go b/checker/checker.go
index 0601fd60..dc4cb5c6 100644
--- a/checker/checker.go
+++ b/checker/checker.go
@@ -249,7 +249,7 @@ func (c *checker) checkSelectField(e, operand *exprpb.Expr, field string, option
 
 	// If the target type was optional coming in, then the result must be optional going out.
 	if isOpt || optional {
-		return decls.NewAbstractType("optional", resultType)
+		return decls.NewOptionalType(resultType)
 	}
 	return resultType
 }
diff --git a/checker/checker_test.go b/checker/checker_test.go
index 37e144a4..89d06570 100644
--- a/checker/checker_test.go
+++ b/checker/checker_test.go
@@ -2073,7 +2073,7 @@ _&&_(_==_(list~type(list(dyn))^list,
 		in: `has(a.dynamic)`,
 		env: testEnv{
 			idents: []*exprpb.Decl{
-				decls.NewVar("a", decls.NewAbstractType("optional", decls.Dyn)),
+				decls.NewVar("a", decls.NewOptionalType(decls.Dyn)),
 			},
 		},
 		outType: decls.Bool,
@@ -2083,7 +2083,7 @@ _&&_(_==_(list~type(list(dyn))^list,
 		in: `has(a.?b.c)`,
 		env: testEnv{
 			idents: []*exprpb.Decl{
-				decls.NewVar("a", decls.NewAbstractType("optional", decls.NewMapType(decls.String, decls.Dyn))),
+				decls.NewVar("a", decls.NewOptionalType(decls.NewMapType(decls.String, decls.Dyn))),
 			},
 		},
 		outType: decls.Bool,