diff --git a/proto/decode.go b/proto/decode.go
index e1177b8..2e2ce8d 100644
--- a/proto/decode.go
+++ b/proto/decode.go
@@ -99,7 +99,7 @@
 	if err != nil {
 		return out, err
 	}
-	if allowPartial {
+	if allowPartial || out.Initialized {
 		return out, nil
 	}
 	return out, isInitialized(m)