diff --git a/object/marshal.go b/object/marshal.go
index 7f47d65..ddd5746 100644
--- a/object/marshal.go
+++ b/object/marshal.go
@@ -1111,17 +1111,13 @@ func (r *PutSingleRequestBody) StableMarshal(buf []byte) []byte {
 
 // SetMarshalData sets marshal data to reduce memory allocations.
 //
-// It is unsafe to modify request data after setting marshal data.
+// It is unsafe to modify/copy request data after setting marshal data.
 func (r *PutSingleRequestBody) SetMarshalData(data []byte) {
 	if r == nil {
 		return
 	}
 
-	if data == nil {
-		r.marshalData = r.StableMarshal(nil)
-	} else {
-		r.marshalData = data
-	}
+	r.marshalData = data
 
 	proto.NestedStructureSetMarshalData(putSingleReqObjectField, r.marshalData, r.object)
 }
diff --git a/util/proto/marshal.go b/util/proto/marshal.go
index 2704960..c944102 100644
--- a/util/proto/marshal.go
+++ b/util/proto/marshal.go
@@ -287,6 +287,11 @@ func NestedStructureSetMarshalData[T any, M setMarshalData[T]](field int64, pare
 		return 0
 	}
 
+	if parentData == nil {
+		v.SetMarshalData(nil)
+		return 0
+	}
+
 	n := v.StableSize()
 	buf := make([]byte, binary.MaxVarintLen64)
 	prefix := protowire.EncodeTag(protowire.Number(field), protowire.BytesType)