diff --git a/include/json/reader.h b/include/json/reader.h
index f983ce9..251d7c6 100644
--- a/include/json/reader.h
+++ b/include/json/reader.h
@@ -320,6 +320,8 @@ public:
     - `"failIfExtra": false or true`
       - If true, `parse()` returns false when extra non-whitespace trails
         the JSON value in the input string.
+    - `"rejectDupKeys": false or true`
+      - If true, `parse()` returns false when a key is duplicated within an object.
 
     You can examine 'settings_` yourself
     to see the defaults. You can also write and read them just like any
diff --git a/src/lib_json/json_reader.cpp b/src/lib_json/json_reader.cpp
index b04b60a..c79abdf 100644
--- a/src/lib_json/json_reader.cpp
+++ b/src/lib_json/json_reader.cpp
@@ -916,6 +916,7 @@ public:
   bool allowNumericKeys_;
   bool allowSingleQuotes_;
   bool failIfExtra_;
+  bool rejectDupKeys_;
   int stackLimit_;
 };  // OurFeatures
 
@@ -1896,6 +1897,7 @@ CharReader* CharReaderBuilder::newCharReader() const
   features.allowSingleQuotes_ = settings_["allowSingleQuotes"].asBool();
   features.stackLimit_ = settings_["stackLimit"].asInt();
   features.failIfExtra_ = settings_["failIfExtra"].asBool();
+  features.rejectDupKeys_ = settings_["rejectDupKeys"].asBool();
   return new OurCharReader(collectComments, features);
 }
 static void getValidReaderKeys(std::set<std::string>* valid_keys)
@@ -1909,6 +1911,7 @@ static void getValidReaderKeys(std::set<std::string>* valid_keys)
   valid_keys->insert("allowSingleQuotes");
   valid_keys->insert("stackLimit");
   valid_keys->insert("failIfExtra");
+  valid_keys->insert("rejectDupKeys");
 }
 bool CharReaderBuilder::validate(Json::Value* invalid) const
 {
@@ -1941,6 +1944,7 @@ void CharReaderBuilder::strictMode(Json::Value* settings)
   (*settings)["allowNumericKeys"] = false;
   (*settings)["allowSingleQuotes"] = false;
   (*settings)["failIfExtra"] = true;
+  (*settings)["rejectDupKeys"] = true;
 //! [CharReaderBuilderStrictMode]
 }
 // static
@@ -1955,6 +1959,7 @@ void CharReaderBuilder::setDefaults(Json::Value* settings)
   (*settings)["allowSingleQuotes"] = false;
   (*settings)["stackLimit"] = 1000;
   (*settings)["failIfExtra"] = false;
+  (*settings)["rejectDupKeys"] = false;
 //! [CharReaderBuilderDefaults]
 }