diff --git a/dagger/spec.go b/dagger/spec.go
index f84b93d0..e061ecac 100644
--- a/dagger/spec.go
+++ b/dagger/spec.go
@@ -29,7 +29,7 @@ func (s Spec) Validate(v *Value, defpath string) (err error) {
 	if err := def.Validate(); err != nil {
 		return err
 	}
-	merged := def.Unwrap().Fill(v)
+	merged := def.Unwrap().Fill(v.Value)
 	if err := merged.Err(); err != nil {
 		return err
 	}