diff --git a/internal/core/validate/validate.go b/internal/core/validate/validate.go
index e1addf4..1af60c4 100644
--- a/internal/core/validate/validate.go
+++ b/internal/core/validate/validate.go
@@ -87,7 +87,7 @@
 		}
 
 	} else if v.checkConcrete() {
-		x := x.Default()
+		x = x.Default()
 		if !adt.IsConcrete(x) {
 			x := x.Value()
 			v.add(&adt.Bottom{
diff --git a/internal/core/validate/validate_test.go b/internal/core/validate/validate_test.go
index f23f6fe..e5ed4ff 100644
--- a/internal/core/validate/validate_test.go
+++ b/internal/core/validate/validate_test.go
@@ -163,6 +163,24 @@
 			c: b + b
 		}
 		`,
+	}, {
+		desc: "pick up non-concrete value in default",
+		cfg:  &Config{Concrete: true},
+		in: `
+		x: null | *{
+			a: int
+		}
+		`,
+		out: "incomplete\nx.a: incomplete value int",
+	}, {
+		desc: "pick up non-concrete value in default",
+		cfg:  &Config{Concrete: true},
+		in: `
+			x: null | *{
+				a: 1 | 2
+			}
+			`,
+		out: "incomplete\nx.a: incomplete value 1 | 2",
 	}}
 
 	r := runtime.New()