diff --git a/index.js b/index.js
index f89081e..a4c321a 100755
--- a/index.js
+++ b/index.js
@@ -88,7 +88,7 @@ const Properties = new Map([
 ]);
 
 const LowConfidenceMode = {
-	noOp: "no-op",
+	keep: "keep",
 	force: "force",
 	exit: "exit"
 };
@@ -162,30 +162,54 @@ let args = yargs
 		defaultCompletion();
 	})
 	.middleware([ yargsCompatProperties, yargsFixPositional ], true) //middleware seems to be buggy
+	.option("help", {
+		alias: 'h',
+		desc: __`Show help`
+	})
+	.option("base", {
+		alias: 'b',
+		type: "string",
+		desc: __`Set the document URL when parsing standard input or a local file (this affects relative links)`
+	})
 	.option("completion", {
 		type: "boolean",
 		desc: __`Print script for bash/zsh completion`
 	})
-	.option("version", {
-		alias: 'V',
+	.option("insane", {
+		alias: 'S',
 		type: "boolean",
-		desc: __`Print version`
+		desc: __`Don't sanitize HTML`
 	})
-	.option("help", {
-		alias: 'h',
-		desc: __`Show help`
+	.option("is-file", {
+		alias: 'f',
+		type: "boolean",
+		desc: __`Interpret SOURCE as a file name rather than a URL`,
+		default: false,
+		hidden: true,
+		//deprecated: true
 	})
-	.option("output", {
-		alias: 'o',
-		type: "string",
-		desc: __`The file to which the result should be output`
+	.option("is-url", {
+		alias: 'U',
+		type: "boolean",
+		desc: __`(deprecated) Interpret SOURCE as a URL rather than file name`,
+		hidden: true,
+		//deprecated: true
+	})
+	.option("json", {
+		alias: 'j',
+		type: "boolean",
+		desc: __`Output properties as a JSON payload`
 	})
 	.option("low-confidence", {
 		alias: 'l',
 		type: "string",
 		desc: __`What to do if Readability.js is uncertain about what the core content actually is`,
 		//default: "no-op", //don't set default because completion won't work
-		choices: ["no-op", "force", "exit"]
+	})
+	.option("output", {
+		alias: 'o',
+		type: "string",
+		desc: __`The file to which the result should be output`
 	})
 	.option("properties", {
 		alias: 'p',
@@ -199,11 +223,6 @@ let args = yargs
 		desc: __`Don't output extra information to stderr`,
 		default: false 
 	})
-	.option("base", {
-		alias: 'b',
-		type: "string",
-		desc: __`Set the document URL when parsing standard input or a local file (this affects relative links)`
-	})
 	.option("url", {
 		alias: 'u',
 		type: "string",
@@ -211,37 +230,17 @@ let args = yargs
 		hidden: true,
 		//deprecated: true //completion script does not respect this value, so just say it in the description
 	})
-	.option("is-file", {
-		alias: 'f',
-		type: "boolean",
-		desc: __`Interpret SOURCE as a file name rather than a URL`,
-		default: false,
-		hidden: true,
-		//deprecated: true
-	})
-	.option("is-url", {
-		alias: 'U',
-		type: "boolean",
-		desc: __`(deprecated) Interpret SOURCE as a URL rather than file name`,
-		hidden: true,
-		//deprecated: true
-	})
-	.option("insane", {
-		alias: 'S',
-		type: "boolean",
-		desc: __`Don't sanitize HTML`
-	})
-	.option("json", {
-		alias: 'j',
+	.option("version", {
+		alias: 'V',
 		type: "boolean",
-		desc: __`Output properties as a JSON payload`
+		desc: __`Print version`
 	})
 	.epilogue(__`The --low-confidence option determines what should be done for documents where Readability can't tell what the core content is:\n` +
-__`   no-op   When unsure, don't touch the HTML, output as-is. This is incompatible with the --properties and --json options.\n` +
+__`   keep    When unsure, don't touch the HTML, output as-is. This is incompatible with the --properties and --json options.\n` +
 __`   force   Process the document even when unsure (may produce really bad output).\n` +
 __`   exit    When unsure, exit with an error.\n` +
   '\n' +
-__`Default value is "no-op".\n` +
+__`Default value is "keep".\n` +
   '\n' +
   '\n' +
 __`The --properties option accepts a list of values, separated by spaces. Suitable values are:\n` +
@@ -261,8 +260,17 @@ __`Default value is "html-title html-content".\n`)
 	.parse();
 
 if (!args["low-confidence"]) {
-	args["low-confidence"] = LowConfidenceMode.noOp;
-	args['l'] = LowConfidenceMode.noOp;
+	args["low-confidence"] = LowConfidenceMode.keep;
+	args['l'] = LowConfidenceMode.keep;
+} else if (args["low-confidence"] == "no-op") {
+	console.error(__`Note: no-op option is deprecated, please use 'keep' instead.`);
+	args["low-confidence"] = LowConfidenceMode.keep;
+	args['l'] = LowConfidenceMode.keep;
+} else if (!Object.values(LowConfidenceMode).includes(args["low-confidence"])) {
+	console.error(__`Unknown mode: ${args["low-confidence"]}\nPlease use one of: keep, force, exit`);
+	console.error(__`Use --help for more info.`);
+	setErrored(ExitCodes.badUsageCLI);
+	process.exit();
 }
 
 if (args["is-url"]) {
diff --git a/locales/en.json b/locales/en.json
index 27eb114..0dda4fd 100644
--- a/locales/en.json
+++ b/locales/en.json
@@ -15,10 +15,10 @@
   "(deprecated) Interpret SOURCE as a URL rather than file name": "(deprecated) Interpret SOURCE as a URL rather than file name",
   "Output properties as a JSON payload": "Output properties as a JSON payload",
   "The --low-confidence option determines what should be done for documents where Readability can't tell what the core content is:\n": "The --low-confidence option determines what should be done for documents where Readability can't tell what the core content is:\n",
-  "   no-op   When unsure, don't touch the HTML, output as-is. This is incompatible with the --properties and --json options.\n": "   no-op   When unsure, don't touch the HTML, output as-is. This is incompatible with the --properties and --json options.\n",
+  "   keep    When unsure, don't touch the HTML, output as-is. This is incompatible with the --properties and --json options.\n": "   keep    When unsure, don't touch the HTML, output as-is. This is incompatible with the --properties and --json options.\n",
   "   force   Process the document even when unsure (may produce really bad output).\n": "   force   Process the document even when unsure (may produce really bad output).\n",
   "   exit    When unsure, exit with an error.\n": "   exit    When unsure, exit with an error.\n",
-  "Default value is \"no-op\".\n": "Default value is \"no-op\".\n",
+  "Default value is \"keep\".\n": "Default value is \"keep\".\n",
   "The --properties option accepts a list of values, separated by spaces. Suitable values are:\n": "The --properties option accepts a list of values, separated by spaces. Suitable values are:\n",
   "   title          The title of the article.\n": "   title          The title of the article.\n",
   "   html-title     The title of the article, wrapped in an <h1> tag.\n": "   html-title     The title of the article, wrapped in an <h1> tag.\n",
@@ -42,5 +42,8 @@
   "Not sure if this document should be processed, exiting": "Not sure if this document should be processed, exiting",
   "Can't output properties": "Can't output properties",
   "Couldn't process document.": "Couldn't process document.",
-  "Host not found: '%s'": "Host not found: '%s'"
+  "Host not found: '%s'": "Host not found: '%s'",
+  "Unknown mode: %s\nPlease use one of: keep, force, exit": "Unknown mode: %s\nPlease use one of: keep, force, exit",
+  "Use --help for more info.": "Use --help for more info.",
+  "Note: no-op option is deprecated, please use 'keep' instead.": "Note: no-op option is deprecated, please use 'keep' instead."
 }
diff --git a/locales/ru.json b/locales/ru.json
index 81a29b4..96ef668 100644
--- a/locales/ru.json
+++ b/locales/ru.json
@@ -15,10 +15,10 @@
   "(deprecated) Interpret SOURCE as a URL rather than file name": "(устаревшее) Интерпретировать [source] как URL, а не как файл",
   "Output properties as a JSON payload": "Показать характеристики текста в формате JSON",
   "The --low-confidence option determines what should be done for documents where Readability can't tell what the core content is:\n": "Параметр --low-confidence определяет, что следует делать, если Readability не может определить целевой контент:\n",
-  "   no-op   When unsure, don't touch the HTML, output as-is. This is incompatible with the --properties and --json options.\n": "   no-op   В случае неуверенности, не трогать HTML, выдавать как есть. Не совместимо с параметрами --properties и --json.\n",
+  "   keep    When unsure, don't touch the HTML, output as-is. This is incompatible with the --properties and --json options.\n": "   keep    В случае неуверенности, не трогать HTML, выдавать как есть. Не совместимо с параметрами --properties и --json.\n",
   "   force   Process the document even when unsure (may produce really bad output).\n": "   force   Обработать документ даже в случае неуверенности (может выдать плохой результат).\n",
   "   exit    When unsure, exit with an error.\n": "   exit    В случае неуверенности, выдать ошибку и выйти.\n",
-  "Default value is \"no-op\".\n": "По умолчанию выполняется \"no-op\".\n",
+  "Default value is \"keep\".\n": "По умолчанию выполняется \"keep\".\n",
   "The --properties option accepts a list of values, separated by spaces. Suitable values are:\n": "Параметр --properties принимает список значений (разделённых пробелами):\n",
   "   title          The title of the article.\n": "   title          Заголовок статьи.\n",
   "   html-title     The title of the article, wrapped in an <h1> tag.\n": "   html-title     Заголовок статьи в тэге <h1>.\n",
@@ -42,5 +42,8 @@
   "Not sure if this document should be processed, exiting": "Не уверен, стоит ли обрабатывать этот документ - выхожу",
   "Can't output properties": "Не могу определить характеристики",
   "Couldn't process document.": "Не удалось обработать документ.",
-  "Host not found: '%s'": "Сервер не найден: '%s'"
+  "Host not found: '%s'": "Сервер не найден: '%s'",
+  "Unknown mode: %s\nPlease use one of: keep, force, exit": "Неизвестный режим: %s\nПожалуйста, используйте один из: keep, force, exit",
+  "Use --help for more info.": "Чтобы узнать больше, воспользуйтесь --help",
+  "Note: no-op option is deprecated, please use 'keep' instead.": "Внимание: параметр no-op устаревшый, используйте вместо него 'keep'."
 }