diff --git a/index.js b/index.js
index 315d1aab..4fd05531 100644
--- a/index.js
+++ b/index.js
@@ -46,7 +46,6 @@ function parse (args, opts) {
     counts: {},
     normalize: {},
     configs: {},
-    defaulted: {},
     nargs: {},
     coercions: {},
     keys: []
@@ -132,14 +131,6 @@ function parse (args, opts) {
   })
 
   var argv = { _: [] }
-
-  Object.keys(flags.bools).forEach(function (key) {
-    if (Object.prototype.hasOwnProperty.call(defaults, key)) {
-      setArg(key, defaults[key])
-      setDefaulted(key)
-    }
-  })
-
   var notFlags = []
 
   for (var i = 0; i < args.length; i++) {
@@ -406,8 +397,6 @@ function parse (args, opts) {
   }
 
   function setArg (key, val) {
-    unsetDefaulted(key)
-
     if (/-/.test(key) && configuration['camel-case-expansion']) {
       var alias = key.split('.').map(function (prop) {
         return camelCase(prop)
@@ -560,7 +549,7 @@ function parse (args, opts) {
       } else {
         // setting arguments via CLI takes precedence over
         // values within the config file.
-        if (!hasKey(argv, fullKey.split('.')) || (flags.defaulted[fullKey]) || (flags.arrays[fullKey] && configuration['combine-arrays'])) {
+        if (!hasKey(argv, fullKey.split('.')) || (flags.arrays[fullKey] && configuration['combine-arrays'])) {
           setArg(fullKey, value)
         }
       }
@@ -589,7 +578,7 @@ function parse (args, opts) {
           return camelCase(key)
         })
 
-        if (((configOnly && flags.configs[keys.join('.')]) || !configOnly) && (!hasKey(argv, keys) || flags.defaulted[keys.join('.')])) {
+        if (((configOnly && flags.configs[keys.join('.')]) || !configOnly) && !hasKey(argv, keys)) {
           setArg(keys.join('.'), process.env[envVar])
         }
       }
@@ -704,7 +693,7 @@ function parse (args, opts) {
       }
     } else if (o[key] === undefined && isTypeArray) {
       o[key] = isValueArray ? value : [value]
-    } else if (duplicate && !(o[key] === undefined || checkAllAliases(key, flags.bools) || checkAllAliases(keys.join('.'), flags.bools) || checkAllAliases(key, flags.counts))) {
+    } else if (duplicate && !(o[key] === undefined || checkAllAliases(key, flags.counts))) {
       o[key] = [ o[key], value ]
     } else {
       o[key] = value
@@ -762,18 +751,6 @@ function parse (args, opts) {
     return isSet
   }
 
-  function setDefaulted (key) {
-    [].concat(flags.aliases[key] || [], key).forEach(function (k) {
-      flags.defaulted[k] = true
-    })
-  }
-
-  function unsetDefaulted (key) {
-    [].concat(flags.aliases[key] || [], key).forEach(function (k) {
-      delete flags.defaulted[k]
-    })
-  }
-
   // make a best effor to pick a default value
   // for an option based on name and type.
   function defaultValue (key) {
diff --git a/test/yargs-parser.js b/test/yargs-parser.js
index c908187b..abcfaafd 100644
--- a/test/yargs-parser.js
+++ b/test/yargs-parser.js
@@ -1108,7 +1108,7 @@ describe('yargs-parser', function () {
         })
       })
 
-      describe('with implied false default', function () {
+      describe('without any default value', function () {
         var opts = null
 
         beforeEach(function () {
@@ -1125,8 +1125,8 @@ describe('yargs-parser', function () {
           parser(['--no-flag'], opts).flag.should.be.false // eslint-disable-line
         })
 
-        it('should set false if no flag in arg', function () {
-          expect(parser([], opts).flag).to.be.undefined // eslint-disable-line
+        it('should not add property if no flag in arg', function () {
+          parser([''], opts).should.not.have.property('flag')
         })
       })
 
@@ -2334,6 +2334,18 @@ describe('yargs-parser', function () {
             parsed['x'].should.deep.equal(3)
           })
         })
+        describe('type=boolean', function () {
+          it('[-x true -x true -x false] => false', function () {
+            var parsed = parser('-x true -x true -x false', {
+              boolean: ['x'],
+              configuration: {
+                'duplicate-arguments-array': false,
+                'flatten-duplicate-arrays': false
+              }
+            })
+            parsed['x'].should.deep.equal(false)
+          })
+        })
       })
       describe('duplicate=false, flatten=true,', function () {
         describe('type=array', function () {
@@ -2370,6 +2382,18 @@ describe('yargs-parser', function () {
             parsed['x'].should.deep.equal(3)
           })
         })
+        describe('type=boolean', function () {
+          it('[-x true -x true -x false] => false', function () {
+            var parsed = parser('-x true -x true -x false', {
+              boolean: ['x'],
+              configuration: {
+                'duplicate-arguments-array': false,
+                'flatten-duplicate-arrays': true
+              }
+            })
+            parsed['x'].should.deep.equal(false)
+          })
+        })
       })
       describe('duplicate=true, flatten=true,', function () {
         describe('type=array', function () {
@@ -2406,6 +2430,18 @@ describe('yargs-parser', function () {
             parsed['x'].should.deep.equal([1, 2, 3])
           })
         })
+        describe('type=boolean', function () {
+          it('[-x true -x true -x false] => [true, true, false]', function () {
+            var parsed = parser('-x true -x true -x false', {
+              boolean: ['x'],
+              configuration: {
+                'duplicate-arguments-array': true,
+                'flatten-duplicate-arrays': true
+              }
+            })
+            parsed['x'].should.deep.equal([true, true, false])
+          })
+        })
       })
       describe('duplicate=true, flatten=false,', function () {
         describe('type=array', function () {
@@ -2442,6 +2478,18 @@ describe('yargs-parser', function () {
             parsed['x'].should.deep.equal([1, 2, 3])
           })
         })
+        describe('type=boolean', function () {
+          it('[-x true -x true -x false] => [true, true, false]', function () {
+            var parsed = parser('-x true -x true -x false', {
+              boolean: ['x'],
+              configuration: {
+                'duplicate-arguments-array': true,
+                'flatten-duplicate-arrays': false
+              }
+            })
+            parsed['x'].should.deep.equal([true, true, false])
+          })
+        })
       })
     })