diff --git a/lib/validation.js b/lib/validation.js
index d44d3507f..17f0d9f30 100644
--- a/lib/validation.js
+++ b/lib/validation.js
@@ -57,10 +57,10 @@ module.exports = function validation (yargs, usage, y18n) {
   // make sure that any args that require an
   // value (--foo=bar), have a value.
   self.missingArgumentValue = function missingArgumentValue (argv) {
-    const defaultValues = [true, false, '', undefined]
     const options = yargs.getOptions()
     if (options.requiresArg.length > 0) {
       const missingRequiredArgs = []
+      const defaultValues = new Set([true, false, ''])
 
       options.requiresArg.forEach((key) => {
         // if the argument is not set in argv no need to check
@@ -71,7 +71,7 @@ module.exports = function validation (yargs, usage, y18n) {
         // if a value is explicitly requested,
         // flag argument as missing if it does not
         // look like foo=bar was entered.
-        if (~defaultValues.indexOf(value) ||
+        if (defaultValues.has(value) ||
           (Array.isArray(value) && !value.length)) {
           missingRequiredArgs.push(key)
         }
diff --git a/test/validation.js b/test/validation.js
index 5e8bafeb9..c37be6c89 100644
--- a/test/validation.js
+++ b/test/validation.js
@@ -369,46 +369,6 @@ describe('validation tests', () => {
         .argv
     })
 
-    it('fails when a required argument of type number is missing', (done) => {
-      yargs('-w')
-        .option('w', {type: 'number', requiresArg: true})
-        .fail((msg) => {
-          msg.should.equal('Missing argument value: w')
-          return done()
-        })
-        .argv
-    })
-
-    it('fails when a required argument of type string is missing', (done) => {
-      yargs('-w')
-        .option('w', {type: 'string', requiresArg: true})
-        .fail((msg) => {
-          msg.should.equal('Missing argument value: w')
-          return done()
-        })
-        .argv
-    })
-
-    it('fails when a required argument of type boolean is missing', (done) => {
-      yargs('-w')
-        .option('w', {type: 'boolean', requiresArg: true})
-        .fail((msg) => {
-          msg.should.equal('Missing argument value: w')
-          return done()
-        })
-        .argv
-    })
-
-    it('fails when a required argument of type array is missing', (done) => {
-      yargs('-w')
-        .option('w', {type: 'array', requiresArg: true})
-        .fail((msg) => {
-          msg.should.equal('Missing argument value: w')
-          return done()
-        })
-        .argv
-    })
-
     it('fails when required arguments are present, but a command is missing', (done) => {
       yargs('-w 10 -m wombat')
         .demand(1, ['w', 'm'])
@@ -419,16 +379,6 @@ describe('validation tests', () => {
         .argv
     })
 
-    // see: https://github.com/yargs/yargs/issues/1041
-    it('does not fail if required argument is not provided', (done) => {
-      yargs('')
-        .option('w', {type: 'array', requiresArg: true})
-        .parse('', (err, argv, output) => {
-          expect(err).to.equal(null)
-          return done()
-        })
-    })
-
     it('fails without a message if msg is null', (done) => {
       yargs([])
         .demand(1, null)
@@ -475,6 +425,69 @@ describe('validation tests', () => {
     })
   })
 
+  describe('requiresArg', () => {
+    it('fails when a required argument value of type number is missing', (done) => {
+      yargs()
+        .option('w', {type: 'number', requiresArg: true})
+        .parse('-w', (err, argv, output) => {
+          expect(err).to.exist
+          expect(err).to.have.property('message', 'Not enough arguments following: w')
+          return done()
+        })
+    })
+
+    it('fails when a required argument value of type string is missing', (done) => {
+      yargs()
+        .option('w', {type: 'string', requiresArg: true})
+        .parse('-w', (err, argv, output) => {
+          expect(err).to.exist
+          expect(err).to.have.property('message', 'Missing argument value: w')
+          return done()
+        })
+    })
+
+    it('fails when a required argument value of type boolean is missing', (done) => {
+      yargs()
+        .option('w', {type: 'boolean', requiresArg: true})
+        .parse('-w', (err, argv, output) => {
+          expect(err).to.exist
+          expect(err).to.have.property('message', 'Missing argument value: w')
+          return done()
+        })
+    })
+
+    it('fails when a required argument value of type array is missing', (done) => {
+      yargs()
+        .option('w', {type: 'array', requiresArg: true})
+        .parse('-w', (err, argv, output) => {
+          expect(err).to.exist
+          expect(err).to.have.property('message', 'Missing argument value: w')
+          return done()
+        })
+    })
+
+    // see: https://github.com/yargs/yargs/issues/1041
+    it('does not fail if argument with required value is not provided', (done) => {
+      yargs()
+        .option('w', {type: 'number', requiresArg: true})
+        .command('woo')
+        .parse('', (err, argv, output) => {
+          expect(err).to.equal(null)
+          return done()
+        })
+    })
+
+    it('does not fail if argument with required value is not provided to subcommand', (done) => {
+      yargs()
+        .option('w', {type: 'number', requiresArg: true})
+        .command('woo')
+        .parse('woo', (err, argv, output) => {
+          expect(err).to.equal(null)
+          return done()
+        })
+    })
+  })
+
   describe('choices', () => {
     it('fails with one invalid value', (done) => {
       yargs(['--state', 'denial'])
diff --git a/yargs.js b/yargs.js
index 524404fb3..0194e9449 100644
--- a/yargs.js
+++ b/yargs.js
@@ -964,6 +964,18 @@ function Yargs (processArgs, cwd, parentRequire) {
 
     options.__ = y18n.__
     options.configuration = pkgUp()['yargs'] || {}
+
+    // numbers are defaulted to `undefined`, which makes it impossible to verify requiresArg
+    // so _unlike_ other types, we will implicitly add them to narg when requiresArg is true
+    const numberTyped = new Set(options.number)
+    options.requiresArg
+      .filter(key => numberTyped.has(key))
+      .forEach(key => {
+        // if narg _and_ requiresArg are configured for an option,
+        // we should probably throw an error somewhere indicating conflicting configuration
+        options.narg[key] = 1
+      })
+
     const parsed = Parser.detailed(args, options)
     let argv = parsed.argv
     if (parseContext) argv = Object.assign({}, argv, parseContext)