diff --git a/include/json/value.h b/include/json/value.h
index 26bb38b..62bee43 100644
--- a/include/json/value.h
+++ b/include/json/value.h
@@ -283,7 +283,7 @@ Json::Value obj_value(Json::objectValue); // {}
 
   /// Deep copy, then swap(other).
   /// \note Over-write existing comments. To preserve comments, use #swapPayload().
-  Value& operator=(Value other);
+  Value &operator=(const Value &other);
   /// Swap everything.
   void swap(Value& other);
   /// Swap values but leave comments and source offsets in place.
diff --git a/src/lib_json/json_value.cpp b/src/lib_json/json_value.cpp
index 8fbce54..5b7e64a 100644
--- a/src/lib_json/json_value.cpp
+++ b/src/lib_json/json_value.cpp
@@ -466,8 +466,9 @@ Value::~Value() {
     delete[] comments_;
 }
 
-Value& Value::operator=(Value other) {
-  swap(other);
+Value &Value::operator=(const Value &other) {
+  Value temp(other);
+  swap(temp);
   return *this;
 }