diff --git a/.swift-version b/.swift-version
index 5186d07..bf77d54 100644
--- a/.swift-version
+++ b/.swift-version
@@ -1 +1 @@
-4.0
+4.2
diff --git a/TunnelKit.xcodeproj/project.pbxproj b/TunnelKit.xcodeproj/project.pbxproj
index 687b0b8..5e7eb7f 100644
--- a/TunnelKit.xcodeproj/project.pbxproj
+++ b/TunnelKit.xcodeproj/project.pbxproj
@@ -665,11 +665,13 @@
 				TargetAttributes = {
 					0E1108991F77B9E800A92462 = {
 						CreatedOnToolsVersion = 9.0;
+						LastSwiftMigration = 1000;
 						ProvisioningStyle = Automatic;
 						TestTargetID = 0E1108A81F77B9F900A92462;
 					};
 					0E1108A81F77B9F900A92462 = {
 						CreatedOnToolsVersion = 9.0;
+						LastSwiftMigration = 1000;
 						ProvisioningStyle = Automatic;
 						SystemCapabilities = {
 							com.apple.ApplicationGroups.iOS = {
@@ -682,6 +684,7 @@
 					};
 					0E17D7F81F730D9F009EE129 = {
 						CreatedOnToolsVersion = 9.0;
+						LastSwiftMigration = 1000;
 						ProvisioningStyle = Automatic;
 					};
 					0E3251C41F95770D00C108D9 = {
@@ -1011,6 +1014,7 @@
 				INFOPLIST_FILE = TunnelKitTests/Info.plist;
 				LD_RUNPATH_SEARCH_PATHS = "$(inherited) @executable_path/Frameworks @loader_path/Frameworks";
 				PRODUCT_NAME = "$(TARGET_NAME)";
+				SWIFT_VERSION = 4.2;
 				TARGETED_DEVICE_FAMILY = "1,2";
 				TEST_HOST = "$(BUILT_PRODUCTS_DIR)/TunnelKitHost.app/TunnelKitHost";
 			};
@@ -1025,6 +1029,7 @@
 				INFOPLIST_FILE = TunnelKitTests/Info.plist;
 				LD_RUNPATH_SEARCH_PATHS = "$(inherited) @executable_path/Frameworks @loader_path/Frameworks";
 				PRODUCT_NAME = "$(TARGET_NAME)";
+				SWIFT_VERSION = 4.2;
 				TARGETED_DEVICE_FAMILY = "1,2";
 				TEST_HOST = "$(BUILT_PRODUCTS_DIR)/TunnelKitHost.app/TunnelKitHost";
 			};
@@ -1042,6 +1047,7 @@
 				LD_RUNPATH_SEARCH_PATHS = "$(inherited) @executable_path/Frameworks";
 				PRODUCT_BUNDLE_IDENTIFIER = com.algoritmico.ios.TunnelKitHost;
 				PRODUCT_NAME = "$(TARGET_NAME)";
+				SWIFT_VERSION = 4.2;
 				TARGETED_DEVICE_FAMILY = "1,2";
 			};
 			name = Debug;
@@ -1058,6 +1064,7 @@
 				LD_RUNPATH_SEARCH_PATHS = "$(inherited) @executable_path/Frameworks";
 				PRODUCT_BUNDLE_IDENTIFIER = com.algoritmico.ios.TunnelKitHost;
 				PRODUCT_NAME = "$(TARGET_NAME)";
+				SWIFT_VERSION = 4.2;
 				TARGETED_DEVICE_FAMILY = "1,2";
 			};
 			name = Release;
@@ -1120,7 +1127,7 @@
 				SDKROOT = iphoneos;
 				SWIFT_ACTIVE_COMPILATION_CONDITIONS = DEBUG;
 				SWIFT_OPTIMIZATION_LEVEL = "-Onone";
-				SWIFT_VERSION = 4.0;
+				SWIFT_VERSION = 4.2;
 				VERSIONING_SYSTEM = "apple-generic";
 				VERSION_INFO_PREFIX = "";
 			};
@@ -1176,7 +1183,7 @@
 				MTL_ENABLE_DEBUG_INFO = NO;
 				SDKROOT = iphoneos;
 				SWIFT_OPTIMIZATION_LEVEL = "-Owholemodule";
-				SWIFT_VERSION = 4.0;
+				SWIFT_VERSION = 4.2;
 				VALIDATE_PRODUCT = YES;
 				VERSIONING_SYSTEM = "apple-generic";
 				VERSION_INFO_PREFIX = "";
diff --git a/TunnelKitHost/AppDelegate.swift b/TunnelKitHost/AppDelegate.swift
index 7624da6..dc5f442 100644
--- a/TunnelKitHost/AppDelegate.swift
+++ b/TunnelKitHost/AppDelegate.swift
@@ -43,7 +43,7 @@ class AppDelegate: UIResponder, UIApplicationDelegate {
     var window: UIWindow?
 
 
-    func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplicationLaunchOptionsKey: Any]?) -> Bool {
+    func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]?) -> Bool {
         // Override point for customization after application launch.
         return true
     }