diff --git a/object/marshal.go b/object/marshal.go
index 18172e6..7f47d65 100644
--- a/object/marshal.go
+++ b/object/marshal.go
@@ -346,16 +346,12 @@ func (o *Object) StableMarshal(buf []byte) []byte {
 
 // SetMarshalData sets marshal data to reduce memory allocations.
 //
-// It is unsafe to modify object data after setting marshal data.
+// It is unsafe to modify/copy object data after setting marshal data.
 func (o *Object) SetMarshalData(data []byte) {
 	if o == nil {
 		return
 	}
-	if data == nil {
-		o.marshalData = o.StableMarshal(nil)
-	} else {
-		o.marshalData = data
-	}
+	o.marshalData = data
 }
 
 func (o *Object) StableSize() (size int) {