diff --git a/src/ripple/json/impl/json_writer.cpp b/src/ripple/json/impl/json_writer.cpp
index c64bfd772f..98cdf59299 100644
--- a/src/ripple/json/impl/json_writer.cpp
+++ b/src/ripple/json/impl/json_writer.cpp
@@ -200,7 +200,7 @@ FastWriter::write ( const Value& root )
     document_ = "";
     writeValue ( root );
     document_ += "\n";
-    return document_;
+    return std::move (document_);
 }