diff --git a/index.js b/index.js
index f2ca6a3..128088d 100644
--- a/index.js
+++ b/index.js
@@ -78,7 +78,5 @@ function commandLineArgs (optionDefinitions, options) {
     }
   }
 
-  const result = output.toObject({ skipUnknown: !options.partial })
-  const optionUtil = require('./lib/option-util')
-  return options.camelCase ? optionUtil.camelCaseObject(result) : result
+  return output.toObject({ skipUnknown: !options.partial, camelCase: options.camelCase })
 }
diff --git a/lib/option-util.js b/lib/option-util.js
deleted file mode 100644
index 65f17bf..0000000
--- a/lib/option-util.js
+++ /dev/null
@@ -1,15 +0,0 @@
-'use strict'
-
-function camelCaseObject (object) {
-  const camelCase = require('lodash.camelcase')
-  for (const prop of Object.keys(object)) {
-    const converted = camelCase(prop)
-    if (converted !== prop) {
-      object[converted] = object[prop]
-      delete object[prop]
-    }
-  }
-  return object
-}
-
-exports.camelCaseObject = camelCaseObject
diff --git a/lib/output-grouped.js b/lib/output-grouped.js
index ace2061..9ca1c77 100644
--- a/lib/output-grouped.js
+++ b/lib/output-grouped.js
@@ -5,6 +5,8 @@ class GroupedOutput extends Output {
   toObject (options) {
     const arrayify = require('array-back')
     const t = require('typical')
+    const camelCase = require('lodash.camelcase')
+    const superOutputNoCamel = super.toObject({ skipUnknown: options.skipUnknown })
     const superOutput = super.toObject(options)
     const unknown = superOutput._unknown
     delete superOutput._unknown
@@ -14,20 +16,22 @@ class GroupedOutput extends Output {
     if (unknown && unknown.length) grouped._unknown = unknown
 
     this.definitions.whereGrouped().forEach(def => {
-      const outputValue = superOutput[def.name]
+      const name = options.camelCase ? camelCase(def.name) : def.name
+      const outputValue = superOutputNoCamel[def.name]
       for (const groupName of arrayify(def.group)) {
         grouped[groupName] = grouped[groupName] || {}
         if (t.isDefined(outputValue)) {
-          grouped[groupName][def.name] = outputValue
+          grouped[groupName][name] = outputValue
         }
       }
     })
 
     this.definitions.whereNotGrouped().forEach(def => {
-      const outputValue = superOutput[def.name]
+      const name = options.camelCase ? camelCase(def.name) : def.name
+      const outputValue = superOutputNoCamel[def.name]
       if (t.isDefined(outputValue)) {
         if (!grouped._none) grouped._none = {}
-        grouped._none[def.name] = outputValue
+        grouped._none[name] = outputValue
       }
     })
     return grouped
diff --git a/lib/output.js b/lib/output.js
index 53eef14..65bad23 100644
--- a/lib/output.js
+++ b/lib/output.js
@@ -21,10 +21,11 @@ class Output extends Map {
   }
 
   toObject (options) {
+    const camelCase = require('lodash.camelcase')
     options = options || {}
     const output = {}
     for (const item of this) {
-      const name = item[0]
+      const name = options.camelCase && item[0] !== '_unknown' ? camelCase(item[0]) : item[0]
       const option = item[1]
       if (name === '_unknown' && !option.get().length) continue
       output[name] = option.get()
diff --git a/package-lock.json b/package-lock.json
index 539b6f6..9d0410a 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -33,6 +33,15 @@
       "integrity": "sha1-SlKCrBZHKek2Gbz9OtFR+BfOkfU=",
       "dev": true
     },
+    "ansi-escape-sequences": {
+      "version": "4.0.0",
+      "resolved": "https://registry.npmjs.org/ansi-escape-sequences/-/ansi-escape-sequences-4.0.0.tgz",
+      "integrity": "sha512-v+0wW9Wezwsyb0uF4aBVCjmSqit3Ru7PZFziGF0o2KwTvN2zWfTi3BRLq9EkJFdg3eBbyERXGTntVpBxH1J68Q==",
+      "dev": true,
+      "requires": {
+        "array-back": "2.0.0"
+      }
+    },
     "argparse": {
       "version": "1.0.9",
       "resolved": "https://registry.npmjs.org/argparse/-/argparse-1.0.9.tgz",
@@ -117,6 +126,12 @@
         "tweetnacl": "0.14.5"
       }
     },
+    "bluebird": {
+      "version": "3.5.1",
+      "resolved": "https://registry.npmjs.org/bluebird/-/bluebird-3.5.1.tgz",
+      "integrity": "sha512-MKiLiV+I1AA596t9w1sQJ8jkiSr5+ZKi0WKrYGUn6d1Fx+Ij4tIj+m2WMQSGczs5jZVxV339chE8iwk6F64wjA==",
+      "dev": true
+    },
     "boom": {
       "version": "4.3.1",
       "resolved": "https://registry.npmjs.org/boom/-/boom-4.3.1.tgz",
@@ -227,9 +242,9 @@
       }
     },
     "command-line-args": {
-      "version": "5.0.0",
-      "resolved": "https://registry.npmjs.org/command-line-args/-/command-line-args-5.0.0.tgz",
-      "integrity": "sha512-jp5PY9xA7pff6TaLS5y10zRqD5Xwsk/kODoIZy+FIKyHwcKFBsMAL3OMwL88VfrpAN706WFWZaPEjDaY5u2/xA==",
+      "version": "5.0.1",
+      "resolved": "https://registry.npmjs.org/command-line-args/-/command-line-args-5.0.1.tgz",
+      "integrity": "sha512-gRJDcIjFSzMcmG/GrJlgL0wWoAxr11mVzCq32bjka0endupm9meLwvoJUKc4HDeFiEIB2X3GvNrhF5cKO4Bd4A==",
       "dev": true,
       "requires": {
         "argv-tools": "0.1.1",
@@ -239,6 +254,19 @@
         "typical": "2.6.1"
       }
     },
+    "command-line-tool": {
+      "version": "0.8.0",
+      "resolved": "https://registry.npmjs.org/command-line-tool/-/command-line-tool-0.8.0.tgz",
+      "integrity": "sha512-Xw18HVx/QzQV3Sc5k1vy3kgtOeGmsKIqwtFFoyjI4bbcpSgnw2CWVULvtakyw4s6fhyAdI6soQQhXc2OzJy62g==",
+      "dev": true,
+      "requires": {
+        "ansi-escape-sequences": "4.0.0",
+        "array-back": "2.0.0",
+        "command-line-args": "5.0.1",
+        "command-line-usage": "4.1.0",
+        "typical": "2.6.1"
+      }
+    },
     "command-line-usage": {
       "version": "4.1.0",
       "resolved": "https://registry.npmjs.org/command-line-usage/-/command-line-usage-4.1.0.tgz",
@@ -249,17 +277,6 @@
         "array-back": "2.0.0",
         "table-layout": "0.4.2",
         "typical": "2.6.1"
-      },
-      "dependencies": {
-        "ansi-escape-sequences": {
-          "version": "4.0.0",
-          "resolved": "https://registry.npmjs.org/ansi-escape-sequences/-/ansi-escape-sequences-4.0.0.tgz",
-          "integrity": "sha512-v+0wW9Wezwsyb0uF4aBVCjmSqit3Ru7PZFziGF0o2KwTvN2zWfTi3BRLq9EkJFdg3eBbyERXGTntVpBxH1J68Q==",
-          "dev": true,
-          "requires": {
-            "array-back": "2.0.0"
-          }
-        }
       }
     },
     "common-sequence": {
@@ -358,6 +375,26 @@
       "integrity": "sha1-3zrhmayt+31ECqrgsp4icrJOxhk=",
       "dev": true
     },
+    "dmd": {
+      "version": "3.0.10",
+      "resolved": "https://registry.npmjs.org/dmd/-/dmd-3.0.10.tgz",
+      "integrity": "sha512-+tRZIFV9fII538XFZSoRP1abtIy55RYa4waGvtKB36LD97NRorWsYT3V3HEURmnXpA4eGIFQph1E2f+51hWrTg==",
+      "dev": true,
+      "requires": {
+        "array-back": "2.0.0",
+        "cache-point": "0.4.1",
+        "common-sequence": "1.0.2",
+        "file-set": "1.1.1",
+        "handlebars": "4.0.11",
+        "marked": "0.3.12",
+        "object-get": "2.1.0",
+        "reduce-flatten": "1.0.1",
+        "reduce-unique": "1.0.0",
+        "reduce-without": "1.0.1",
+        "test-value": "3.0.0",
+        "walk-back": "3.0.0"
+      }
+    },
     "ecc-jsbn": {
       "version": "0.1.1",
       "resolved": "https://registry.npmjs.org/ecc-jsbn/-/ecc-jsbn-0.1.1.tgz",
@@ -593,6 +630,15 @@
         "esprima": "4.0.0"
       }
     },
+    "js2xmlparser": {
+      "version": "3.0.0",
+      "resolved": "https://registry.npmjs.org/js2xmlparser/-/js2xmlparser-3.0.0.tgz",
+      "integrity": "sha1-P7YOqgicVED5MZ9RdgzNB+JJlzM=",
+      "dev": true,
+      "requires": {
+        "xmlcreate": "1.0.2"
+      }
+    },
     "jsbn": {
       "version": "0.1.1",
       "resolved": "https://registry.npmjs.org/jsbn/-/jsbn-0.1.1.tgz",
@@ -618,32 +664,23 @@
         "strip-json-comments": "2.0.1",
         "taffydb": "2.6.2",
         "underscore": "1.8.3"
-      },
-      "dependencies": {
-        "bluebird": {
-          "version": "3.5.1",
-          "resolved": "https://registry.npmjs.org/bluebird/-/bluebird-3.5.1.tgz",
-          "integrity": "sha512-MKiLiV+I1AA596t9w1sQJ8jkiSr5+ZKi0WKrYGUn6d1Fx+Ij4tIj+m2WMQSGczs5jZVxV339chE8iwk6F64wjA==",
-          "dev": true
-        },
-        "js2xmlparser": {
-          "version": "3.0.0",
-          "resolved": "https://registry.npmjs.org/js2xmlparser/-/js2xmlparser-3.0.0.tgz",
-          "integrity": "sha1-P7YOqgicVED5MZ9RdgzNB+JJlzM=",
-          "dev": true,
-          "requires": {
-            "xmlcreate": "1.0.2"
-          }
-        },
-        "klaw": {
-          "version": "2.0.0",
-          "resolved": "https://registry.npmjs.org/klaw/-/klaw-2.0.0.tgz",
-          "integrity": "sha1-WcEo4Nxc5BAgEVEZTuucv4WGUPY=",
-          "dev": true,
-          "requires": {
-            "graceful-fs": "4.1.11"
-          }
-        }
+      }
+    },
+    "jsdoc-api": {
+      "version": "4.0.1",
+      "resolved": "https://registry.npmjs.org/jsdoc-api/-/jsdoc-api-4.0.1.tgz",
+      "integrity": "sha512-qCzHGQxfd9toMRjQft9E44Y40zWDPgf13pt3n+xExk8+wmVd7aueW6cTSQOHyjQG1v07INunQD8AcCAPxhZVmw==",
+      "dev": true,
+      "requires": {
+        "array-back": "2.0.0",
+        "cache-point": "0.4.1",
+        "collect-all": "1.0.3",
+        "file-set": "1.1.1",
+        "fs-then-native": "2.0.0",
+        "jsdoc": "3.5.5",
+        "object-to-spawn-args": "1.1.1",
+        "temp-path": "1.0.0",
+        "walk-back": "3.0.0"
       }
     },
     "jsdoc-parse": {
@@ -673,67 +710,6 @@
         "jsdoc-api": "4.0.1",
         "jsdoc-parse": "3.0.1",
         "walk-back": "3.0.0"
-      },
-      "dependencies": {
-        "ansi-escape-sequences": {
-          "version": "4.0.0",
-          "resolved": "https://registry.npmjs.org/ansi-escape-sequences/-/ansi-escape-sequences-4.0.0.tgz",
-          "integrity": "sha512-v+0wW9Wezwsyb0uF4aBVCjmSqit3Ru7PZFziGF0o2KwTvN2zWfTi3BRLq9EkJFdg3eBbyERXGTntVpBxH1J68Q==",
-          "dev": true,
-          "requires": {
-            "array-back": "2.0.0"
-          }
-        },
-        "command-line-tool": {
-          "version": "0.8.0",
-          "resolved": "https://registry.npmjs.org/command-line-tool/-/command-line-tool-0.8.0.tgz",
-          "integrity": "sha512-Xw18HVx/QzQV3Sc5k1vy3kgtOeGmsKIqwtFFoyjI4bbcpSgnw2CWVULvtakyw4s6fhyAdI6soQQhXc2OzJy62g==",
-          "dev": true,
-          "requires": {
-            "ansi-escape-sequences": "4.0.0",
-            "array-back": "2.0.0",
-            "command-line-args": "5.0.0",
-            "command-line-usage": "4.1.0",
-            "typical": "2.6.1"
-          }
-        },
-        "dmd": {
-          "version": "3.0.10",
-          "resolved": "https://registry.npmjs.org/dmd/-/dmd-3.0.10.tgz",
-          "integrity": "sha512-+tRZIFV9fII538XFZSoRP1abtIy55RYa4waGvtKB36LD97NRorWsYT3V3HEURmnXpA4eGIFQph1E2f+51hWrTg==",
-          "dev": true,
-          "requires": {
-            "array-back": "2.0.0",
-            "cache-point": "0.4.1",
-            "common-sequence": "1.0.2",
-            "file-set": "1.1.1",
-            "handlebars": "4.0.11",
-            "marked": "0.3.12",
-            "object-get": "2.1.0",
-            "reduce-flatten": "1.0.1",
-            "reduce-unique": "1.0.0",
-            "reduce-without": "1.0.1",
-            "test-value": "3.0.0",
-            "walk-back": "3.0.0"
-          }
-        },
-        "jsdoc-api": {
-          "version": "4.0.1",
-          "resolved": "https://registry.npmjs.org/jsdoc-api/-/jsdoc-api-4.0.1.tgz",
-          "integrity": "sha512-qCzHGQxfd9toMRjQft9E44Y40zWDPgf13pt3n+xExk8+wmVd7aueW6cTSQOHyjQG1v07INunQD8AcCAPxhZVmw==",
-          "dev": true,
-          "requires": {
-            "array-back": "2.0.0",
-            "cache-point": "0.4.1",
-            "collect-all": "1.0.3",
-            "file-set": "1.1.1",
-            "fs-then-native": "2.0.0",
-            "jsdoc": "3.5.5",
-            "object-to-spawn-args": "1.1.1",
-            "temp-path": "1.0.0",
-            "walk-back": "3.0.0"
-          }
-        }
       }
     },
     "json-schema": {
@@ -775,6 +751,15 @@
         "is-buffer": "1.1.6"
       }
     },
+    "klaw": {
+      "version": "2.0.0",
+      "resolved": "https://registry.npmjs.org/klaw/-/klaw-2.0.0.tgz",
+      "integrity": "sha1-WcEo4Nxc5BAgEVEZTuucv4WGUPY=",
+      "dev": true,
+      "requires": {
+        "graceful-fs": "4.1.11"
+      }
+    },
     "lazy-cache": {
       "version": "1.0.4",
       "resolved": "https://registry.npmjs.org/lazy-cache/-/lazy-cache-1.0.4.tgz",
@@ -1225,21 +1210,10 @@
       "requires": {
         "ansi-escape-sequences": "4.0.0",
         "array-back": "2.0.0",
-        "command-line-args": "5.0.0",
+        "command-line-args": "5.0.1",
         "command-line-usage": "4.1.0",
         "file-set": "1.1.1",
         "reduce-flatten": "1.0.1"
-      },
-      "dependencies": {
-        "ansi-escape-sequences": {
-          "version": "4.0.0",
-          "resolved": "https://registry.npmjs.org/ansi-escape-sequences/-/ansi-escape-sequences-4.0.0.tgz",
-          "integrity": "sha512-v+0wW9Wezwsyb0uF4aBVCjmSqit3Ru7PZFziGF0o2KwTvN2zWfTi3BRLq9EkJFdg3eBbyERXGTntVpBxH1J68Q==",
-          "dev": true,
-          "requires": {
-            "array-back": "2.0.0"
-          }
-        }
       }
     },
     "test-value": {
diff --git a/test/camel-case.js b/test/camel-case.js
index ce17b94..0a2ed60 100644
--- a/test/camel-case.js
+++ b/test/camel-case.js
@@ -5,7 +5,7 @@ const a = require('assert')
 
 const runner = new TestRunner()
 
-runner.test('camel-case', function () {
+runner.test('camel-case: regular', function () {
   const optionDefinitions = [
     { name: 'one-two' },
     { name: 'three', type: Boolean }
@@ -17,3 +17,62 @@ runner.test('camel-case', function () {
     three: true
   })
 })
+
+runner.test('camel-case: grouped', function () {
+  const optionDefinitions = [
+    { name: 'one-one', group: 'a' },
+    { name: 'two-two', group: 'a' },
+    { name: 'three-three', group: 'b', type: Boolean },
+    { name: 'four-four' }
+  ]
+  const argv = [ '--one-one', '1', '--two-two', '2', '--three-three', '--four-four', '4' ]
+  const result = commandLineArgs(optionDefinitions, { argv, camelCase: true })
+  a.deepStrictEqual(result, {
+    a: {
+      oneOne: '1',
+      twoTwo: '2'
+    },
+    b: {
+      threeThree: true
+    },
+    _all: {
+      oneOne: '1',
+      twoTwo: '2',
+      threeThree: true,
+      fourFour: '4'
+    },
+    _none: {
+      fourFour: '4'
+    }
+  })
+})
+
+runner.test('camel-case: grouped with unknowns', function () {
+  const optionDefinitions = [
+    { name: 'one-one', group: 'a' },
+    { name: 'two-two', group: 'a' },
+    { name: 'three-three', group: 'b', type: Boolean },
+    { name: 'four-four' }
+  ]
+  const argv = [ '--one-one', '1', '--two-two', '2', '--three-three', '--four-four', '4', '--five' ]
+  const result = commandLineArgs(optionDefinitions, { argv, camelCase: true, partial: true })
+  a.deepStrictEqual(result, {
+    a: {
+      oneOne: '1',
+      twoTwo: '2'
+    },
+    b: {
+      threeThree: true
+    },
+    _all: {
+      oneOne: '1',
+      twoTwo: '2',
+      threeThree: true,
+      fourFour: '4'
+    },
+    _none: {
+      fourFour: '4'
+    },
+    _unknown: [ '--five' ]
+  })
+})
diff --git a/test/grouping.js b/test/grouping.js
index e415094..39d8384 100644
--- a/test/grouping.js
+++ b/test/grouping.js
@@ -118,3 +118,57 @@ runner.test('groups: two ungrouped, both set', function () {
     _none: { three: '3', four: '4' }
   })
 })
+
+runner.test('groups: with partial', function () {
+  const definitions = [
+    { name: 'one', group: 'a' },
+    { name: 'two', group: 'a' },
+    { name: 'three', group: 'b' }
+  ]
+  const argv = [ '--one', '1', '--two', '2', '--three', '3', 'ham', '--cheese' ]
+  a.deepStrictEqual(commandLineArgs(definitions, { argv, partial: true }), {
+    a: {
+      one: '1',
+      two: '2'
+    },
+    b: {
+      three: '3'
+    },
+    _all: {
+      one: '1',
+      two: '2',
+      three: '3'
+    },
+    _unknown: [ 'ham', '--cheese' ]
+  })
+})
+
+runner.test('partial: with partial, multiple groups and _none', function () {
+  const definitions = [
+    { name: 'one', group: ['a', 'f'] },
+    { name: 'two', group: ['a', 'g'] },
+    { name: 'three' }
+  ]
+  const argv = [ '--cheese', '--one', '1', 'ham', '--two', '2', '--three', '3', '-c' ]
+  a.deepStrictEqual(commandLineArgs(definitions, { argv, partial: true }), {
+    a: {
+      one: '1',
+      two: '2'
+    },
+    f: {
+      one: '1'
+    },
+    g: {
+      two: '2'
+    },
+    _none: {
+      three: '3'
+    },
+    _all: {
+      one: '1',
+      two: '2',
+      three: '3'
+    },
+    _unknown: [ '--cheese', 'ham', '-c' ]
+  })
+})
diff --git a/test/partial.js b/test/partial.js
index 8da4747..3fa6d0c 100644
--- a/test/partial.js
+++ b/test/partial.js
@@ -159,60 +159,6 @@ runner.test('unknown options: rejected defaultOption values end up in _unknown',
   })
 })
 
-runner.test('partial: groups', function () {
-  const definitions = [
-    { name: 'one', group: 'a' },
-    { name: 'two', group: 'a' },
-    { name: 'three', group: 'b' }
-  ]
-  const argv = [ '--one', '1', '--two', '2', '--three', '3', 'ham', '--cheese' ]
-  a.deepStrictEqual(commandLineArgs(definitions, { argv, partial: true }), {
-    a: {
-      one: '1',
-      two: '2'
-    },
-    b: {
-      three: '3'
-    },
-    _all: {
-      one: '1',
-      two: '2',
-      three: '3'
-    },
-    _unknown: [ 'ham', '--cheese' ]
-  })
-})
-
-runner.test('partial: multiple groups and _none', function () {
-  const definitions = [
-    { name: 'one', group: ['a', 'f'] },
-    { name: 'two', group: ['a', 'g'] },
-    { name: 'three' }
-  ]
-  const argv = [ '--cheese', '--one', '1', 'ham', '--two', '2', '--three', '3', '-c' ]
-  a.deepStrictEqual(commandLineArgs(definitions, { argv, partial: true }), {
-    a: {
-      one: '1',
-      two: '2'
-    },
-    f: {
-      one: '1'
-    },
-    g: {
-      two: '2'
-    },
-    _none: {
-      three: '3'
-    },
-    _all: {
-      one: '1',
-      two: '2',
-      three: '3'
-    },
-    _unknown: [ '--cheese', 'ham', '-c' ]
-  })
-})
-
 runner.test('partial: defaultOption with --option=value notation', function () {
   const definitions = [
     { name: 'files', type: String, multiple: true, defaultOption: true }