diff --git a/.swift-version b/.swift-version
index 9f55b2ccb..5186d0706 100644
--- a/.swift-version
+++ b/.swift-version
@@ -1 +1 @@
-3.0
+4.0
diff --git a/.travis.yml b/.travis.yml
index 28d4fc6e5..74ada6418 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -1,4 +1,4 @@
-osx_image: xcode8.3
+osx_image: xcode9
 language: objective-c
 env:
   global:
diff --git a/README.md b/README.md
index 00d39f90b..6dc27a843 100644
--- a/README.md
+++ b/README.md
@@ -4,7 +4,7 @@
 [![Carthage compatible](https://img.shields.io/badge/Carthage-compatible-4BC51D.svg?style=flat)](https://github.com/Carthage/Carthage)
 
 # PhoneNumberKit
-Swift 3.0 framework for parsing, formatting and validating international phone numbers.
+Swift 4.0 framework for parsing, formatting and validating international phone numbers.
 Inspired by Google's libphonenumber.
 
 [Migrating from PhoneNumberKit 0.x? See the migration guide.](https://github.com/marmelroy/PhoneNumberKit/blob/master/Documentation/OXMIGRATIONGUIDE.md)  
diff --git a/build.sh b/build.sh
index 611f95b5a..fa1db3702 100755
--- a/build.sh
+++ b/build.sh
@@ -1,7 +1,7 @@
 #!/bin/bash
 
 # **** Update me when new Xcode versions are released! ****
-PLATFORM="platform=iOS Simulator,OS=10.3.1,name=iPhone 7"
+PLATFORM="platform=iOS Simulator,OS=11.0,name=iPhone 8"
 SDK="iphonesimulator"