diff --git a/lib/command.js b/lib/command.js
index d8bfc9a3f..8f2d30071 100644
--- a/lib/command.js
+++ b/lib/command.js
@@ -52,7 +52,7 @@ class Command extends EventEmitter {
     this._enablePositionalOptions = false;
     this._passThroughOptions = false;
     this._lifeCycleHooks = {}; // a hash of arrays
-    /** @type {boolean | string} */
+    /** @type {(boolean | string)} */
     this._showHelpAfterError = false;
     this._showSuggestionAfterError = true;
 
@@ -141,7 +141,7 @@ class Command extends EventEmitter {
    *   .command('stop [service]', 'stop named service, or all if no name supplied');
    *
    * @param {string} nameAndArgs - command name and arguments, args are `<required>` or `[optional]` and last may also be `variadic...`
-   * @param {Object|string} [actionOptsOrExecDesc] - configuration options (for action), or description (for executable)
+   * @param {(Object|string)} [actionOptsOrExecDesc] - configuration options (for action), or description (for executable)
    * @param {Object} [execOpts] - configuration options (for executable)
    * @return {Command} returns new command for action handler, or `this` for executable command
    */
@@ -203,7 +203,7 @@ class Command extends EventEmitter {
    * or with a subclass of Help by overriding createHelp().
    *
    * @param {Object} [configuration] - configuration options
-   * @return {Command|Object} `this` command for chaining, or stored configuration
+   * @return {(Command|Object)} `this` command for chaining, or stored configuration
    */
 
   configureHelp(configuration) {
@@ -229,7 +229,7 @@ class Command extends EventEmitter {
    *     outputError(str, write) // used for displaying errors, and not used for displaying help
    *
    * @param {Object} [configuration] - configuration options
-   * @return {Command|Object} `this` command for chaining, or stored configuration
+   * @return {(Command|Object)} `this` command for chaining, or stored configuration
    */
 
   configureOutput(configuration) {
@@ -242,7 +242,7 @@ class Command extends EventEmitter {
   /**
    * Display the help or a custom message after an error occurs.
    *
-   * @param {boolean|string} [displayHelp]
+   * @param {(boolean|string)} [displayHelp]
    * @return {Command} `this` command for chaining
    */
   showHelpAfterError(displayHelp = true) {
@@ -316,7 +316,7 @@ class Command extends EventEmitter {
    *
    * @param {string} name
    * @param {string} [description]
-   * @param {Function|*} [fn] - custom argument processing function
+   * @param {(Function|*)} [fn] - custom argument processing function
    * @param {*} [defaultValue]
    * @return {Command} `this` command for chaining
    */
@@ -517,7 +517,7 @@ Expecting one of '${allowedValues.join("', '")}'`);
   /**
    * Wrap parseArgs to catch 'commander.invalidArgument'.
    *
-   * @param {Option | Argument} target
+   * @param {(Option | Argument)} target
    * @param {string} value
    * @param {*} previous
    * @param {string} invalidArgumentMessage
@@ -691,7 +691,7 @@ Expecting one of '${allowedValues.join("', '")}'`);
    *
    * @param {string} flags
    * @param {string} [description]
-   * @param {Function|*} [parseArg] - custom option processing function or default value
+   * @param {(Function|*)} [parseArg] - custom option processing function or default value
    * @param {*} [defaultValue]
    * @return {Command} `this` command for chaining
    */
@@ -708,7 +708,7 @@ Expecting one of '${allowedValues.join("', '")}'`);
   *
   * @param {string} flags
   * @param {string} [description]
-  * @param {Function|*} [parseArg] - custom option processing function or default value
+  * @param {(Function|*)} [parseArg] - custom option processing function or default value
   * @param {*} [defaultValue]
   * @return {Command} `this` command for chaining
   */
@@ -725,7 +725,7 @@ Expecting one of '${allowedValues.join("', '")}'`);
    * program.combineFlagAndOptionalValue(true);  // `-f80` is treated like `--flag=80`, this is the default behaviour
    * program.combineFlagAndOptionalValue(false) // `-fb` is treated like `-f -b`
    *
-   * @param {Boolean} [combine=true] - if `true` or omitted, an optional value can be specified directly after the flag.
+   * @param {boolean} [combine=true] - if `true` or omitted, an optional value can be specified directly after the flag.
    */
   combineFlagAndOptionalValue(combine = true) {
     this._combineFlagAndOptionalValue = !!combine;
@@ -735,7 +735,7 @@ Expecting one of '${allowedValues.join("', '")}'`);
   /**
    * Allow unknown options on the command line.
    *
-   * @param {Boolean} [allowUnknown=true] - if `true` or omitted, no error will be thrown
+   * @param {boolean} [allowUnknown=true] - if `true` or omitted, no error will be thrown
    * for unknown options.
    */
   allowUnknownOption(allowUnknown = true) {
@@ -746,7 +746,7 @@ Expecting one of '${allowedValues.join("', '")}'`);
   /**
    * Allow excess command-arguments on the command line. Pass false to make excess arguments an error.
    *
-   * @param {Boolean} [allowExcess=true] - if `true` or omitted, no error will be thrown
+   * @param {boolean} [allowExcess=true] - if `true` or omitted, no error will be thrown
    * for excess arguments.
    */
   allowExcessArguments(allowExcess = true) {
@@ -759,7 +759,7 @@ Expecting one of '${allowedValues.join("', '")}'`);
    * subcommands reuse the same option names, and also enables subcommands to turn on passThroughOptions.
    * The default behaviour is non-positional and global options may appear anywhere on the command line.
    *
-   * @param {Boolean} [positional=true]
+   * @param {boolean} [positional=true]
    */
   enablePositionalOptions(positional = true) {
     this._enablePositionalOptions = !!positional;
@@ -772,7 +772,7 @@ Expecting one of '${allowedValues.join("', '")}'`);
    * positional options to have been enabled on the program (parent commands).
    * The default behaviour is non-positional and options may appear before or after command-arguments.
    *
-   * @param {Boolean} [passThrough=true]
+   * @param {boolean} [passThrough=true]
    * for unknown options.
    */
   passThroughOptions(passThrough = true) {
@@ -1229,9 +1229,9 @@ Expecting one of '${allowedValues.join("', '")}'`);
   /**
    * Once we have a promise we chain, but call synchronously until then.
    *
-   * @param {Promise|undefined} promise
+   * @param {(Promise|undefined)} promise
    * @param {Function} fn
-   * @return {Promise|undefined}
+   * @return {(Promise|undefined)}
    * @private
    */
 
@@ -1247,9 +1247,9 @@ Expecting one of '${allowedValues.join("', '")}'`);
 
   /**
    *
-   * @param {Promise|undefined} promise
+   * @param {(Promise|undefined)} promise
    * @param {string} event
-   * @return {Promise|undefined}
+   * @return {(Promise|undefined)}
    * @private
    */
 
@@ -1278,10 +1278,10 @@ Expecting one of '${allowedValues.join("', '")}'`);
 
   /**
    *
-   * @param {Promise|undefined} promise
+   * @param {(Promise|undefined)} promise
    * @param {Command} subCommand
    * @param {string} event
-   * @return {Promise|undefined}
+   * @return {(Promise|undefined)}
    * @private
    */
 
@@ -1477,8 +1477,8 @@ Expecting one of '${allowedValues.join("', '")}'`);
    *     sub --unknown uuu op => [sub], [--unknown uuu op]
    *     sub -- --unknown uuu op => [sub --unknown uuu op], []
    *
-   * @param {String[]} argv
-   * @return {{operands: String[], unknown: String[]}}
+   * @param {string[]} argv
+   * @return {{operands: string[], unknown: string[]}}
    */
 
   parseOptions(argv) {
@@ -1857,7 +1857,7 @@ Expecting one of '${allowedValues.join("', '")}'`);
    * @param {string} [str]
    * @param {string} [flags]
    * @param {string} [description]
-   * @return {this | string | undefined} `this` command for chaining, or version string if no arguments
+   * @return {(this | string | undefined)} `this` command for chaining, or version string if no arguments
    */
 
   version(str, flags, description) {
@@ -1881,7 +1881,7 @@ Expecting one of '${allowedValues.join("', '")}'`);
    *
    * @param {string} [str]
    * @param {Object} [argsDescription]
-   * @return {string|Command}
+   * @return {(string|Command)}
    */
   description(str, argsDescription) {
     if (str === undefined && argsDescription === undefined) return this._description;
@@ -1896,7 +1896,7 @@ Expecting one of '${allowedValues.join("', '")}'`);
    * Set the summary. Used when listed as subcommand of parent.
    *
    * @param {string} [str]
-   * @return {string|Command}
+   * @return {(string|Command)}
    */
   summary(str) {
     if (str === undefined) return this._summary;
@@ -1910,7 +1910,7 @@ Expecting one of '${allowedValues.join("', '")}'`);
    * You may call more than once to add multiple aliases. Only the first alias is shown in the auto-generated help.
    *
    * @param {string} [alias]
-   * @return {string|Command}
+   * @return {(string|Command)}
    */
 
   alias(alias) {
@@ -1941,7 +1941,7 @@ Expecting one of '${allowedValues.join("', '")}'`);
    * Only the first alias is shown in the auto-generated help.
    *
    * @param {string[]} [aliases]
-   * @return {string[]|Command}
+   * @return {(string[]|Command)}
    */
 
   aliases(aliases) {
@@ -1956,7 +1956,7 @@ Expecting one of '${allowedValues.join("', '")}'`);
    * Set / get the command usage `str`.
    *
    * @param {string} [str]
-   * @return {String|Command}
+   * @return {(string|Command)}
    */
 
   usage(str) {
@@ -1981,7 +1981,7 @@ Expecting one of '${allowedValues.join("', '")}'`);
    * Get or set the name of the command.
    *
    * @param {string} [str]
-   * @return {string|Command}
+   * @return {(string|Command)}
    */
 
   name(str) {
@@ -2018,7 +2018,7 @@ Expecting one of '${allowedValues.join("', '")}'`);
    * program.executableDir('subcommands');
    *
    * @param {string} [path]
-   * @return {string|null|Command}
+   * @return {(string|null|Command)}
    */
 
   executableDir(path) {
@@ -2100,7 +2100,7 @@ Expecting one of '${allowedValues.join("', '")}'`);
    * flags and help description for your command. Pass in false to
    * disable the built-in help option.
    *
-   * @param {string | boolean} [flags]
+   * @param {(string | boolean)} [flags]
    * @param {string} [description]
    * @return {Command} `this` command for chaining
    */
@@ -2145,7 +2145,7 @@ Expecting one of '${allowedValues.join("', '")}'`);
    * and 'beforeAll' or 'afterAll' to affect this command and all its subcommands.
    *
    * @param {string} position - before or after built-in help
-   * @param {string | Function} text - string to add, or a function returning a string
+   * @param {(string | Function)} text - string to add, or a function returning a string
    * @return {Command} `this` command for chaining
    */
   addHelpText(position, text) {
diff --git a/lib/option.js b/lib/option.js
index 456b918bd..f06190168 100644
--- a/lib/option.js
+++ b/lib/option.js
@@ -74,7 +74,7 @@ class Option {
    * new Option('--rgb').conflicts('cmyk');
    * new Option('--js').conflicts(['ts', 'jsx']);
    *
-   * @param {string | string[]} names
+   * @param {(string | string[])} names
    * @return {Option}
    */