diff --git a/lib/argsert.js b/lib/argsert.js
index c9a055a5d..d3e72fce5 100644
--- a/lib/argsert.js
+++ b/lib/argsert.js
@@ -1,54 +1,60 @@
 const command = require('./command')()
+const YError = require('./yerror')
 
 const positionName = ['first', 'second', 'third', 'fourth', 'fifth', 'sixth']
 
 module.exports = function (expected, callerArguments, length) {
-  // preface the argument description with "cmd", so
-  // that we can run it through yargs' command parser.
-  var position = 0
-  var parsed = {demanded: [], optional: []}
-  if (typeof expected === 'object') {
-    length = callerArguments
-    callerArguments = expected
-  } else {
-    parsed = command.parseCommand('cmd ' + expected)
-  }
-  const args = [].slice.call(callerArguments)
+  // TODO: should this eventually raise an exception.
+  try {
+    // preface the argument description with "cmd", so
+    // that we can run it through yargs' command parser.
+    var position = 0
+    var parsed = {demanded: [], optional: []}
+    if (typeof expected === 'object') {
+      length = callerArguments
+      callerArguments = expected
+    } else {
+      parsed = command.parseCommand('cmd ' + expected)
+    }
+    const args = [].slice.call(callerArguments)
 
-  while (args.length && args[args.length - 1] === undefined) args.pop()
-  length = length || args.length
+    while (args.length && args[args.length - 1] === undefined) args.pop()
+    length = length || args.length
 
-  if (length < parsed.demanded.length) {
-    throw Error('Not enough arguments provided. Expected ' + parsed.demanded.length +
-      ' but received ' + args.length + '.')
-  }
+    if (length < parsed.demanded.length) {
+      throw new YError('Not enough arguments provided. Expected ' + parsed.demanded.length +
+        ' but received ' + args.length + '.')
+    }
 
-  const totalCommands = parsed.demanded.length + parsed.optional.length
-  if (length > totalCommands) {
-    throw Error('Too many arguments provided. Expected max ' + totalCommands +
-      ' but received ' + length + '.')
-  }
+    const totalCommands = parsed.demanded.length + parsed.optional.length
+    if (length > totalCommands) {
+      throw new YError('Too many arguments provided. Expected max ' + totalCommands +
+        ' but received ' + length + '.')
+    }
 
-  parsed.demanded.forEach(function (demanded) {
-    const arg = args.shift()
-    const observedType = guessType(arg)
-    const matchingTypes = demanded.cmd.filter(function (type) {
-      return type === observedType || type === '*'
+    parsed.demanded.forEach(function (demanded) {
+      const arg = args.shift()
+      const observedType = guessType(arg)
+      const matchingTypes = demanded.cmd.filter(function (type) {
+        return type === observedType || type === '*'
+      })
+      if (matchingTypes.length === 0) argumentTypeError(observedType, demanded.cmd, position, false)
+      position += 1
     })
-    if (matchingTypes.length === 0) argumentTypeError(observedType, demanded.cmd, position, false)
-    position += 1
-  })
 
-  parsed.optional.forEach(function (optional) {
-    if (args.length === 0) return
-    const arg = args.shift()
-    const observedType = guessType(arg)
-    const matchingTypes = optional.cmd.filter(function (type) {
-      return type === observedType || type === '*'
+    parsed.optional.forEach(function (optional) {
+      if (args.length === 0) return
+      const arg = args.shift()
+      const observedType = guessType(arg)
+      const matchingTypes = optional.cmd.filter(function (type) {
+        return type === observedType || type === '*'
+      })
+      if (matchingTypes.length === 0) argumentTypeError(observedType, optional.cmd, position, true)
+      position += 1
     })
-    if (matchingTypes.length === 0) argumentTypeError(observedType, optional.cmd, position, true)
-    position += 1
-  })
+  } catch (err) {
+    console.warn(err.stack)
+  }
 }
 
 function guessType (arg) {
@@ -61,6 +67,6 @@ function guessType (arg) {
 }
 
 function argumentTypeError (observedType, allowedTypes, position, optional) {
-  throw Error('Invalid ' + (positionName[position] || 'manyith') + ' argument.' +
+  throw new YError('Invalid ' + (positionName[position] || 'manyith') + ' argument.' +
     ' Expected ' + allowedTypes.join(' or ') + ' but received ' + observedType + '.')
 }
diff --git a/test/argsert.js b/test/argsert.js
index 07262bc3b..9139d0d0e 100644
--- a/test/argsert.js
+++ b/test/argsert.js
@@ -1,98 +1,143 @@
 /* global describe, it */
 
 const argsert = require('../lib/argsert')
-const expect = require('chai').expect
+const checkOutput = require('./helpers/utils').checkOutput
 
 require('chai').should()
 
 describe('Argsert', function () {
-  it('does not throw exception if optional argument is not provided', function () {
-    argsert('[object]', [].slice.call(arguments))
+  it('does not warn if optional argument is not provided', function () {
+    var o = checkOutput(function () {
+      argsert('[object]', [].slice.call(arguments))
+    })
+
+    o.warnings.length.should.equal(0)
   })
 
-  it('throws exception if wrong type is provided for optional argument', function () {
-    function foo (opts) {
-      argsert('[object|number]', [].slice.call(arguments))
-    }
-    expect(function () {
+  it('warn if wrong type is provided for optional argument', function () {
+    var o = checkOutput(function () {
+      function foo (opts) {
+        argsert('[object|number]', [].slice.call(arguments))
+      }
+
       foo('hello')
-    }).to.throw(/Invalid first argument. Expected object or number but received string./)
+    })
+
+    o.warnings[0].should.match(/Invalid first argument. Expected object or number but received string./)
   })
 
-  it('does not throw exception if optional argument is valid', function () {
-    function foo (opts) {
-      argsert('[object]', [].slice.call(arguments))
-    }
-    foo({foo: 'bar'})
+  it('does not warn if optional argument is valid', function () {
+    var o = checkOutput(function () {
+      function foo (opts) {
+        argsert('[object]', [].slice.call(arguments))
+      }
+
+      foo({foo: 'bar'})
+    })
+
+    o.warnings.length.should.equal(0)
   })
 
-  it('throws exception if required argument is not provided', function () {
-    expect(function () {
+  it('warns if required argument is not provided', function () {
+    var o = checkOutput(function () {
       argsert('<object>', [].slice.call(arguments))
-    }).to.throw(/Not enough arguments provided. Expected 1 but received 0./)
+    })
+
+    o.warnings[0].should.match(/Not enough arguments provided. Expected 1 but received 0./)
   })
 
-  it('throws exception if required argument is of wrong type', function () {
-    function foo (opts) {
-      argsert('<object>', [].slice.call(arguments))
-    }
-    expect(function () {
+  it('warns if required argument is of wrong type', function () {
+    var o = checkOutput(function () {
+      function foo (opts) {
+        argsert('<object>', [].slice.call(arguments))
+      }
+
       foo('bar')
-    }).to.throw(/Invalid first argument. Expected object but received string./)
+    })
+
+    o.warnings[0].should.match(/Invalid first argument. Expected object but received string./)
   })
 
   it('supports a combination of required and optional arguments', function () {
-    function foo (opts) {
-      argsert('<array> <string|object> [string|object]', [].slice.call(arguments))
-    }
-    foo([], 'foo', {})
+    var o = checkOutput(function () {
+      function foo (opts) {
+        argsert('<array> <string|object> [string|object]', [].slice.call(arguments))
+      }
+
+      foo([], 'foo', {})
+    })
+
+    o.warnings.length.should.equal(0)
   })
 
-  it('throws an exception if too many arguments are provided', function () {
-    function foo (expected) {
-      argsert('<array> [batman]', [].slice.call(arguments))
-    }
-    expect(function () {
+  it('warns if too many arguments are provided', function () {
+    var o = checkOutput(function () {
+      function foo (expected) {
+        argsert('<array> [batman]', [].slice.call(arguments))
+      }
+
       foo([], 33, 99)
-    }).to.throw(/Too many arguments provided. Expected max 2 but received 3./)
+    })
+
+    o.warnings[0].should.match(/Too many arguments provided. Expected max 2 but received 3./)
   })
 
   it('configures function to accept 0 parameters, if only arguments object is provided', function () {
-    function foo (expected) {
-      argsert([].slice.call(arguments))
-    }
-    expect(function () {
+    var o = checkOutput(function () {
+      function foo (expected) {
+        argsert([].slice.call(arguments))
+      }
+
       foo(99)
-    }).to.throw(/Too many arguments provided. Expected max 0 but received 1./)
+    })
+
+    o.warnings[0].should.match(/Too many arguments provided. Expected max 0 but received 1./)
   })
 
   it('allows for any type if * is provided', function () {
-    function foo (opts) {
-      argsert('<*>', [].slice.call(arguments))
-    }
-    foo('bar')
+    var o = checkOutput(function () {
+      function foo (opts) {
+        argsert('<*>', [].slice.call(arguments))
+      }
+
+      foo('bar')
+    })
+
+    o.warnings.length.should.equal(0)
   })
 
   it('should ignore trailing undefined values', function () {
-    function foo (opts) {
-      argsert('<*>', [].slice.call(arguments))
-    }
-    foo('bar', undefined, undefined)
+    var o = checkOutput(function () {
+      function foo (opts) {
+        argsert('<*>', [].slice.call(arguments))
+      }
+
+      foo('bar', undefined, undefined)
+    })
+
+    o.warnings.length.should.equal(0)
   })
 
   it('should not ignore undefined values that are not trailing', function () {
-    function foo (opts) {
-      argsert('<*>', [].slice.call(arguments))
-    }
-    expect(function () {
+    var o = checkOutput(function () {
+      function foo (opts) {
+        argsert('<*>', [].slice.call(arguments))
+      }
+
       foo('bar', undefined, undefined, 33)
-    }).to.throw(/Too many arguments provided. Expected max 1 but received 4./)
+    })
+
+    o.warnings[0].should.match(/Too many arguments provided. Expected max 1 but received 4./)
   })
 
   it('supports null as special type', function () {
-    function foo (arg) {
-      argsert('<null>', [].slice.call(arguments))
-    }
-    foo(null)
+    var o = checkOutput(function () {
+      function foo (arg) {
+        argsert('<null>', [].slice.call(arguments))
+      }
+      foo(null)
+    })
+
+    o.warnings.length.should.equal(0)
   })
 })
diff --git a/test/helpers/utils.js b/test/helpers/utils.js
index d896dae67..5a2ccc4f9 100644
--- a/test/helpers/utils.js
+++ b/test/helpers/utils.js
@@ -10,6 +10,7 @@ exports.checkOutput = function (f, argv, cb) {
   var _argv = process.argv
   var _error = console.error
   var _log = console.log
+  var _warn = console.warn
 
   process.exit = function () { exit = true }
   process.env = Hash.merge(process.env, { _: 'node' })
@@ -17,9 +18,11 @@ exports.checkOutput = function (f, argv, cb) {
 
   var errors = []
   var logs = []
+  var warnings = []
 
   console.error = function (msg) { errors.push(msg) }
   console.log = function (msg) { logs.push(msg) }
+  console.warn = function (msg) { warnings.push(msg) }
 
   var result
 
@@ -57,6 +60,7 @@ exports.checkOutput = function (f, argv, cb) {
 
     console.error = _error
     console.log = _log
+    console.warn = _warn
   }
 
   function done () {
@@ -65,6 +69,7 @@ exports.checkOutput = function (f, argv, cb) {
     return {
       errors: errors,
       logs: logs,
+      warnings: warnings,
       exit: exit,
       result: result
     }