diff --git a/src/config/project/index.js b/src/config/project/index.js
index 7a29d8ac..e970e243 100644
--- a/src/config/project/index.js
+++ b/src/config/project/index.js
@@ -8,7 +8,7 @@ let { is, mergeEnvVars } = require('../../lib')
  * Get the project-level configuration, overlaying arc.aws settings (if present)
  */
 module.exports = function getProjectConfig (params) {
-  let { arc, errors, raw, filepath, inventory, _testing } = params
+  let { arc, errors, raw, filepath, inventory } = params
   let _project = {
     ...inventory._project,
     arc,
@@ -26,7 +26,7 @@ module.exports = function getProjectConfig (params) {
   // Parse local and global project preferences
   let scopes = [ 'global', 'local' ]
   for (let scope of scopes) {
-    let p = prefs({ scope, inventory, errors, _testing })
+    let p = prefs({ scope, inventory, errors })
     if (p) {
       // Set up the scoped metadata
       _project[`${scope}Preferences`] = p.preferences
diff --git a/src/config/project/prefs/index.js b/src/config/project/prefs/index.js
index c4bab529..f6ada23f 100644
--- a/src/config/project/prefs/index.js
+++ b/src/config/project/prefs/index.js
@@ -4,20 +4,13 @@ let read = require('../../../read')
 let validate = require('../validate')
 let { is, validationPatterns: valid } = require('../../../lib')
 let { parse } = require('./dotenv')
-let { homedir } = require('os')
+let os = require('os')
 
-module.exports = function getPrefs ({ scope, inventory, errors, _testing }) {
+module.exports = function getPrefs ({ scope, inventory, errors }) {
   let cwd = scope === 'global'
-    ? homedir()
+    ? os.homedir()
     : inventory._project.cwd
 
-  /* istanbul ignore next */
-  if (_testing && scope === 'global') {
-    let _homedir = homedir()
-    if (process.platform === 'win32') _homedir = _homedir.replace(/^[A-Z]:\\/, '')
-    cwd = join(inventory._project.cwd, _homedir)
-  }
-
   let envFilepath = join(cwd, '.env')
   let hasEnvFile = scope === 'local' && existsSync(envFilepath)
   let prefs = read({ type: 'preferences', cwd, errors })
diff --git a/src/index.js b/src/index.js
index d974d821..35f2174d 100644
--- a/src/index.js
+++ b/src/index.js
@@ -32,7 +32,7 @@ module.exports = function architectInventory (params = {}, callback) {
 
   // Always ensure we have a working dir
   params.cwd = params.cwd || process.cwd()
-  let { cwd, rawArc, _testing } = params
+  let { cwd, rawArc } = params
 
   // Stateless inventory run
   if (rawArc) {
@@ -60,7 +60,7 @@ module.exports = function architectInventory (params = {}, callback) {
   let inventory = inventoryDefaults(params)
 
   // Set up project params for config
-  let project = { arc, cwd, errors, filepath, inventory, raw, _testing }
+  let project = { arc, cwd, errors, filepath, inventory, raw }
 
   // Populate inventory.arc
   inventory._arc = config._arc(project)
diff --git a/test/integration/preferences-test.js b/test/integration/preferences-test.js
index 626bd7a7..40ec56d2 100644
--- a/test/integration/preferences-test.js
+++ b/test/integration/preferences-test.js
@@ -3,15 +3,16 @@ let test = require('tape')
 let mockTmp = require('mock-tmp')
 let cwd = process.cwd()
 let testLibPath = join(cwd, 'test', 'lib')
-let { getHomedir } = require(testLibPath)
+let { overrideHomedir } = require(testLibPath)
 let sut = join(cwd, 'src', 'index')
 let inv = require(sut)
 
-let _homedir = getHomedir()
 let mock = join(cwd, 'test', 'mock')
-let arc = '@app\nappname\n@events\nan-event' // Not using @http so we can skip ASAP filesystem checks
-let reset = () => mockTmp.reset()
-let _testing = true
+let globalPrefsFile = '.prefs.arc'
+let reset = () => {
+  mockTmp.reset()
+  overrideHomedir.reset()
+}
 
 /**
  * Duplicates some unit tests as part of the larger whole integration test
@@ -24,6 +25,7 @@ test('Set up env', t => {
 
 test('Get global preferences', t => {
   t.plan(11)
+  let cwd = join(mock, 'prefs', 'global')
   let prefs = {
     sandbox: { environment: 'testing' },
     'sandbox-startup': [
@@ -59,12 +61,11 @@ testing
   env_var_1 foo
   env_var_2 bar
 `
-  let path = join(_homedir, '.prefs.arc')
-  let cwd = mockTmp({
-    'app.arc': arc,
-    [path]: prefsText
+  let tmp = mockTmp({
+    [globalPrefsFile]: prefsText
   })
-  inv({ cwd, _testing }, (err, result) => {
+  overrideHomedir(tmp)
+  inv({ cwd }, (err, result) => {
     if (err) t.fail(err)
     else {
       let { inv, get } = result
@@ -81,7 +82,7 @@ testing
       delete inv._project.globalPreferences._arc
       delete inv._project.globalPreferences._raw
       t.deepEqual(inv._project.globalPreferences, prefs, 'Got correct global preferences')
-      t.equal(inv._project.globalPreferencesFile, join(cwd, path), 'Got correct preferences file')
+      t.equal(inv._project.globalPreferencesFile, join(tmp, globalPrefsFile), 'Got correct preferences file')
       t.teardown(reset)
     }
   })
@@ -135,6 +136,7 @@ test('Get local preferences', t => {
 
 test('Layer local preferences over global preferences', t => {
   t.plan(14)
+  let cwd = join(mock, 'prefs', 'local-over-global')
   let globalPrefsText = `
 @sandbox
 environment testing
@@ -160,19 +162,6 @@ testing
       production: null,
     }
   }
-  let localPrefsText = `
-@sandbox
-environment staging
-
-@create
-autocreate true
-
-@env
-testing
-  env_var_2 bar
-staging
-  env_var_3 fiz
-`
   let localPrefs = {
     sandbox: {
       environment: 'staging',
@@ -201,13 +190,11 @@ staging
       production: null,
     }
   }
-  let path = join(_homedir, '.prefs.arc')
-  let cwd = mockTmp({
-    'app.arc': arc,
-    [path]: globalPrefsText,
-    'preferences.arc': localPrefsText
+  let tmp = mockTmp({
+    [globalPrefsFile]: globalPrefsText,
   })
-  inv({ cwd, _testing }, (err, result) => {
+  overrideHomedir(tmp)
+  inv({ cwd }, (err, result) => {
     if (err) t.fail(err)
     else {
       let { inv, get } = result
@@ -228,7 +215,7 @@ staging
       delete inv._project.localPreferences._raw
       t.deepEqual(inv._project.globalPreferences, globalPrefs, 'Got correct global preferences')
       t.deepEqual(inv._project.localPreferences, localPrefs, 'Got correct local preferences')
-      t.equal(inv._project.globalPreferencesFile, join(cwd, path), 'Got correct preferences file')
+      t.equal(inv._project.globalPreferencesFile, join(tmp, globalPrefsFile), 'Got correct preferences file')
       t.equal(inv._project.localPreferencesFile, join(cwd, 'preferences.arc'), 'Got correct preferences file')
       t.teardown(reset)
     }
diff --git a/test/lib/index.js b/test/lib/index.js
index 620e3c53..23aeb6cd 100644
--- a/test/lib/index.js
+++ b/test/lib/index.js
@@ -1,10 +1,18 @@
-let { homedir } = require('os')
+let os = require('os')
 let { is } = require('../../src/lib')
 
-function getHomedir () {
-  let _homedir = homedir()
-  if (process.platform === 'win32') _homedir = _homedir.replace(/^[A-Z]:\\/, '')
-  return _homedir
+let homedirBak
+let tmpHomedir
+function overrideHomedir (tmp) {
+  if (tmp) tmpHomedir = tmp
+  if (!homedirBak) homedirBak = os.homedir
+  os.homedir = () => tmpHomedir
+}
+overrideHomedir.reset = () => {
+  if (homedirBak) {
+    os.homedir = homedirBak
+    homedirBak = undefined
+  }
 }
 
 function setterPluginSetup (setter, fns) {
@@ -18,6 +26,6 @@ function setterPluginSetup (setter, fns) {
 }
 
 module.exports = {
-  getHomedir,
+  overrideHomedir,
   setterPluginSetup,
 }
diff --git a/test/mock/prefs/global/app.arc b/test/mock/prefs/global/app.arc
new file mode 100644
index 00000000..b28bb98c
--- /dev/null
+++ b/test/mock/prefs/global/app.arc
@@ -0,0 +1,5 @@
+@app
+an-app
+
+@events
+an-event
diff --git a/test/mock/prefs/local-over-global/app.arc b/test/mock/prefs/local-over-global/app.arc
new file mode 100644
index 00000000..b28bb98c
--- /dev/null
+++ b/test/mock/prefs/local-over-global/app.arc
@@ -0,0 +1,5 @@
+@app
+an-app
+
+@events
+an-event
diff --git a/test/mock/prefs/local-over-global/preferences.arc b/test/mock/prefs/local-over-global/preferences.arc
new file mode 100644
index 00000000..53e86b05
--- /dev/null
+++ b/test/mock/prefs/local-over-global/preferences.arc
@@ -0,0 +1,11 @@
+@sandbox
+environment staging
+
+@create
+autocreate true
+
+@env
+testing
+  env_var_2 bar
+staging
+  env_var_3 fiz
diff --git a/test/mock/prefs/local/app.arc b/test/mock/prefs/local/app.arc
new file mode 100644
index 00000000..b28bb98c
--- /dev/null
+++ b/test/mock/prefs/local/app.arc
@@ -0,0 +1,5 @@
+@app
+an-app
+
+@events
+an-event
diff --git a/test/mock/prefs/local/prefs.arc b/test/mock/prefs/local/prefs.arc
new file mode 100644
index 00000000..5a77337f
--- /dev/null
+++ b/test/mock/prefs/local/prefs.arc
@@ -0,0 +1,6 @@
+@env
+testing
+  foo bar
+
+@create
+autocreate true
diff --git a/test/unit/src/config/project/index-test.js b/test/unit/src/config/project/index-test.js
index 88629fa9..f5f85512 100644
--- a/test/unit/src/config/project/index-test.js
+++ b/test/unit/src/config/project/index-test.js
@@ -3,7 +3,7 @@ let test = require('tape')
 let mockTmp = require('mock-tmp')
 let cwd = process.cwd()
 let testLibPath = join(cwd, 'test', 'lib')
-let { getHomedir } = require(testLibPath)
+let { overrideHomedir } = require(testLibPath)
 let inventoryDefaultsPath = join(process.cwd(), 'src', 'defaults')
 let inventoryDefaults = require(inventoryDefaultsPath)
 let defaultFunctionConfigPath = join(process.cwd(), 'src', 'defaults', 'function-config')
@@ -11,10 +11,9 @@ let defaultFunctionConfig = require(defaultFunctionConfigPath)
 let sut = join(cwd, 'src', 'config', 'project')
 let getProjectConfig = require(sut)
 
+let mock = join(cwd, 'test', 'mock')
 let localPrefsFile = 'prefs.arc'
-let _homedir = getHomedir()
-let globalPrefsFile = join(_homedir, 'prefs.arc')
-let _testing = true
+let globalPrefsFile = '.prefs.arc'
 
 test('Set up env', t => {
   t.plan(1)
@@ -67,17 +66,10 @@ test('Project preferences', t => {
   t.plan(29)
   let arc = {}
   let errors = []
-  let cwd, inventory, proj
+  let cwd, inventory, proj, tmp
 
   // Local preferences only
-  let localPrefs = `@env
-testing
-  foo bar
-@create
-autocreate true`
-  cwd = mockTmp({
-    [localPrefsFile]: localPrefs
-  })
+  cwd = join(mock, 'prefs', 'local')
   inventory = inventoryDefaults({ cwd })
   proj = getProjectConfig({ arc, errors, inventory })
   t.equal(errors.length, 0, 'Did not error')
@@ -90,7 +82,6 @@ autocreate true`
   t.equal(proj.globalPreferences, null, 'Did not populate globalPreferences')
   t.equal(proj.globalPreferencesFile, null, 'Did not populate globalPreferencesFile')
   t.equal(proj.env.local.testing.foo, 'bar', 'Populated env local/testing')
-  mockTmp.reset()
 
   // Global preferences only
   let globalPrefs = `@env
@@ -98,11 +89,12 @@ testing
   fiz buz
 @sandbox
 useAWS true`
-  cwd = mockTmp({
+  tmp = mockTmp({
     [globalPrefsFile]: globalPrefs
   })
-  inventory = inventoryDefaults({ cwd })
-  proj = getProjectConfig({ arc, errors, inventory, _testing })
+  overrideHomedir(tmp)
+  inventory = inventoryDefaults({ cwd: process.cwd() })
+  proj = getProjectConfig({ arc, errors, inventory })
   t.equal(errors.length, 0, 'Did not error')
   t.ok(proj.preferences, 'Populated preferences')
   t.equal(proj.preferences.env.testing.fiz, 'buz', 'Populated testing env')
@@ -110,17 +102,17 @@ useAWS true`
   t.equal(proj.localPreferences, null, 'Did not populate localPreferences')
   t.equal(proj.localPreferencesFile, null, 'Did not populate localPreferencesFile')
   t.ok(proj.globalPreferences, 'Populated globalPreferences')
-  t.equal(proj.globalPreferencesFile, join(cwd, globalPrefsFile), 'Populated globalPreferencesFile')
+  t.equal(proj.globalPreferencesFile, join(tmp, globalPrefsFile), 'Populated globalPreferencesFile')
   t.equal(proj.env.local.testing.fiz, 'buz', 'Populated env local/testing')
   mockTmp.reset()
 
   // Merge local + global preferences
-  cwd = mockTmp({
-    [localPrefsFile]: localPrefs,
+  tmp = mockTmp({
     [globalPrefsFile]: globalPrefs,
   })
+  overrideHomedir(tmp)
   inventory = inventoryDefaults({ cwd })
-  proj = getProjectConfig({ arc, errors, inventory, _testing })
+  proj = getProjectConfig({ arc, errors, inventory })
   t.equal(errors.length, 0, 'Did not error')
   t.ok(proj.preferences, 'Populated preferences')
   t.equal(proj.preferences.env.testing.foo, 'bar', 'Populated testing env (preferred local to global prefs)')
@@ -129,9 +121,10 @@ useAWS true`
   t.ok(proj.localPreferences, 'Populated localPreferences')
   t.equal(proj.localPreferencesFile, join(cwd, localPrefsFile), 'Populated localPreferencesFile')
   t.ok(proj.globalPreferences, 'Populated globalPreferences')
-  t.equal(proj.globalPreferencesFile, join(cwd, globalPrefsFile), 'Populated globalPreferencesFile')
+  t.equal(proj.globalPreferencesFile, join(tmp, globalPrefsFile), 'Populated globalPreferencesFile')
   t.equal(proj.env.local.testing.foo, 'bar', 'Populated env local/testing (preferred local to global prefs)')
   mockTmp.reset()
+  overrideHomedir.reset()
 })
 
 test('Project plugins', t => {
diff --git a/test/unit/src/config/project/prefs/index-test.js b/test/unit/src/config/project/prefs/index-test.js
index 6bba19ae..80e56604 100644
--- a/test/unit/src/config/project/prefs/index-test.js
+++ b/test/unit/src/config/project/prefs/index-test.js
@@ -3,21 +3,22 @@ let test = require('tape')
 let mockTmp = require('mock-tmp')
 let cwd = process.cwd()
 let testLibPath = join(cwd, 'test', 'lib')
-let { getHomedir } = require(testLibPath)
+let { overrideHomedir } = require(testLibPath)
 let inventoryDefaultsPath = join(cwd, 'src', 'defaults')
 let inventoryDefaults = require(inventoryDefaultsPath)
 let sut = join(cwd, 'src', 'config', 'project', 'prefs')
 let getPrefs = require(sut)
 
-let _homedir = getHomedir()
-let path = join(_homedir, '.prefs.arc')
-let reset = () => mockTmp.restore()
+let path = '.prefs.arc'
+let reset = () => {
+  mockTmp.reset()
+  overrideHomedir.reset()
+}
 function clean (preferences) {
   // Delete the meta stuff so the actual preferences match during an equality check
   delete preferences._arc
   delete preferences._raw
 }
-let _testing = true
 
 test('Set up env', t => {
   t.plan(1)
@@ -70,13 +71,14 @@ testing
   env_var_1 foo
   env_var_2 bar
 `
-  let cwd = mockTmp({
+  let tmp = mockTmp({
     [path]: prefsText
   })
+  overrideHomedir(tmp)
   let inventory = inventoryDefaults({ cwd })
 
   let errors = []
-  let { preferences, preferencesFile } = getPrefs({ scope: 'global', inventory, errors, _testing })
+  let { preferences, preferencesFile } = getPrefs({ scope: 'global', inventory, errors })
   t.ok(preferences, 'Got preferences')
   t.ok(preferences._arc, 'Got (arc object)')
   t.ok(preferences._raw, 'Got (raw file)')
@@ -202,12 +204,13 @@ test('Get preferences (only unknown items)', t => {
 @idk
 userland true
 `
-  let cwd = mockTmp({
+  let tmp = mockTmp({
     [path]: prefsText
   })
+  overrideHomedir(tmp)
   let inventory = inventoryDefaults({ cwd })
   let errors = []
-  let { preferences, preferencesFile } = getPrefs({ scope: 'global', inventory, errors, _testing })
+  let { preferences, preferencesFile } = getPrefs({ scope: 'global', inventory, errors })
   t.ok(preferences, 'Got preferences')
   t.ok(preferences._arc, 'Got (arc object)')
   t.ok(preferences._raw, 'Got (raw file)')
@@ -221,17 +224,18 @@ userland true
 test('Validate preferences', t => {
   t.plan(7)
   let mock = () => mockTmp({ [path]: prefsText })
-  let cwd, errors, inventory, prefsText
+  let errors, inventory, prefsText, tmp
 
   // Invalid @sandbox env
   prefsText = `
 @sandbox
 env foo
 `
-  cwd = mock()
+  tmp = mock()
+  overrideHomedir(tmp)
   inventory = inventoryDefaults({ cwd })
   errors = []
-  getPrefs({ scope: 'global', inventory, errors, _testing })
+  getPrefs({ scope: 'global', inventory, errors })
   t.equal(errors.length, 1, `Invalid preferences errored: ${errors[0]}`)
 
   // Invalid @env pragma
@@ -239,10 +243,11 @@ env foo
 @env
 foo
 `
-  cwd = mock()
+  tmp = mock()
+  overrideHomedir(tmp)
   inventory = inventoryDefaults({ cwd })
   errors = []
-  getPrefs({ scope: 'global', inventory, errors, _testing })
+  getPrefs({ scope: 'global', inventory, errors })
   t.equal(errors.length, 1, `Invalid preferences errored: ${errors[0]}`)
 
   // Invalid @env environments
@@ -251,10 +256,11 @@ foo
 staging
   foo
 `
-  cwd = mock()
+  tmp = mock()
+  overrideHomedir(tmp)
   inventory = inventoryDefaults({ cwd })
   errors = []
-  getPrefs({ scope: 'global', inventory, errors, _testing })
+  getPrefs({ scope: 'global', inventory, errors })
   t.equal(errors.length, 1, `Invalid preferences errored: ${errors[0]}`)
 
   prefsText = `
@@ -262,10 +268,11 @@ staging
 staging
   env-var-1 foo
 `
-  cwd = mock()
+  tmp = mock()
+  overrideHomedir(tmp)
   inventory = inventoryDefaults({ cwd })
   errors = []
-  getPrefs({ scope: 'global', inventory, errors, _testing })
+  getPrefs({ scope: 'global', inventory, errors })
   t.equal(errors.length, 1, `Invalid preferences errored: ${errors[0]}`)
 
   prefsText = `
@@ -276,10 +283,11 @@ testing
 
 staging
 `
-  cwd = mock()
+  tmp = mock()
+  overrideHomedir(tmp)
   inventory = inventoryDefaults({ cwd })
   errors = []
-  getPrefs({ scope: 'global', inventory, errors, _testing })
+  getPrefs({ scope: 'global', inventory, errors })
   t.equal(errors.length, 1, `Invalid preferences errored: ${errors[0]}`)
 
   prefsText = `
@@ -294,10 +302,11 @@ production
   env_var_1 foo
   env_var_2 bar
 `
-  cwd = mock()
+  tmp = mock()
+  overrideHomedir(tmp)
   inventory = inventoryDefaults({ cwd })
   errors = []
-  getPrefs({ scope: 'global', inventory, errors, _testing })
+  getPrefs({ scope: 'global', inventory, errors })
   t.equal(errors.length, 1, `Invalid preferences errored: ${errors[0]}`)
 
   prefsText = `
@@ -308,10 +317,11 @@ staging
   env_var_1 foo
   env_var_2 bar
 `
-  cwd = mock()
+  tmp = mock()
+  overrideHomedir(tmp)
   inventory = inventoryDefaults({ cwd })
   errors = []
-  getPrefs({ scope: 'global', inventory, errors, _testing })
+  getPrefs({ scope: 'global', inventory, errors })
   t.equal(errors.length, 1, `Invalid preferences errored: ${errors[0]}`)
 
   t.teardown(reset)