diff --git a/src/lib_json/json_value.cpp b/src/lib_json/json_value.cpp
index e6eb345..17a8455 100644
--- a/src/lib_json/json_value.cpp
+++ b/src/lib_json/json_value.cpp
@@ -234,7 +234,7 @@ Value::CZString::CZString(const CZString& other)
   storage_.policy_ = static_cast<unsigned>(other.cstr_
                  ? (static_cast<DuplicationPolicy>(other.storage_.policy_) == noDuplication
                      ? noDuplication : duplicate)
-                 : static_cast<DuplicationPolicy>(other.storage_.policy_));
+                 : static_cast<DuplicationPolicy>(other.storage_.policy_)) & 3U;
   storage_.length_ = other.storage_.length_;
 }