diff --git a/MTMR.xcodeproj/project.pbxproj b/MTMR.xcodeproj/project.pbxproj
index e2179bb..4251a02 100644
--- a/MTMR.xcodeproj/project.pbxproj
+++ b/MTMR.xcodeproj/project.pbxproj
@@ -348,7 +348,7 @@
 				TargetAttributes = {
 					B082B24E205C7D8000BC04DC = {
 						CreatedOnToolsVersion = 9.2;
-						LastSwiftMigration = 1020;
+						LastSwiftMigration = 1000;
 						ProvisioningStyle = Manual;
 						SystemCapabilities = {
 							com.apple.Sandbox = {
@@ -358,7 +358,7 @@
 					};
 					B082B260205C7D8000BC04DC = {
 						CreatedOnToolsVersion = 9.2;
-						LastSwiftMigration = 1020;
+						LastSwiftMigration = 1000;
 					};
 				};
 			};
@@ -622,7 +622,7 @@
 				PRODUCT_NAME = "$(TARGET_NAME)";
 				PROVISIONING_PROFILE_SPECIFIER = "";
 				SWIFT_OBJC_BRIDGING_HEADER = "MTMR/CBridge/TouchBarPrivateApi-Bridging.h";
-				SWIFT_VERSION = 5.0;
+				SWIFT_VERSION = 4.2;
 			};
 			name = Debug;
 		};
@@ -645,7 +645,7 @@
 				PRODUCT_NAME = "$(TARGET_NAME)";
 				PROVISIONING_PROFILE_SPECIFIER = "";
 				SWIFT_OBJC_BRIDGING_HEADER = "MTMR/CBridge/TouchBarPrivateApi-Bridging.h";
-				SWIFT_VERSION = 5.0;
+				SWIFT_VERSION = 4.2;
 			};
 			name = Release;
 		};
@@ -658,7 +658,7 @@
 				LD_RUNPATH_SEARCH_PATHS = "$(inherited) @executable_path/../Frameworks @loader_path/../Frameworks";
 				PRODUCT_BUNDLE_IDENTIFIER = Toxblh.MTMRTests;
 				PRODUCT_NAME = "$(TARGET_NAME)";
-				SWIFT_VERSION = 5.0;
+				SWIFT_VERSION = 4.2;
 			};
 			name = Debug;
 		};
@@ -673,7 +673,7 @@
 				LD_RUNPATH_SEARCH_PATHS = "$(inherited) @executable_path/../Frameworks @loader_path/../Frameworks";
 				PRODUCT_BUNDLE_IDENTIFIER = Toxblh.MTMRTests;
 				PRODUCT_NAME = "$(TARGET_NAME)";
-				SWIFT_VERSION = 5.0;
+				SWIFT_VERSION = 4.2;
 			};
 			name = Release;
 		};
diff --git a/MTMR/AppDelegate.swift b/MTMR/AppDelegate.swift
index b57c7dc..d6adfe5 100644
--- a/MTMR/AppDelegate.swift
+++ b/MTMR/AppDelegate.swift
@@ -51,7 +51,7 @@ class AppDelegate: NSObject, NSApplicationDelegate {
         }
 
         if frontmostApplicationIdentifier != nil {
-            isBlockedApp = blacklistAppIdentifiers.firstIndex(of: frontmostApplicationIdentifier!) != nil
+            isBlockedApp = blacklistAppIdentifiers.index(of: frontmostApplicationIdentifier!) != nil
         } else {
             isBlockedApp = false
         }
@@ -76,7 +76,7 @@ class AppDelegate: NSObject, NSApplicationDelegate {
     @objc func toggleBlackListedApp(_: Any?) {
         let appIdentifier = TouchBarController.shared.frontmostApplicationIdentifier
         if appIdentifier != nil {
-            if let index = TouchBarController.shared.blacklistAppIdentifiers.firstIndex(of: appIdentifier!) {
+            if let index = TouchBarController.shared.blacklistAppIdentifiers.index(of: appIdentifier!) {
                 TouchBarController.shared.blacklistAppIdentifiers.remove(at: index)
             } else {
                 TouchBarController.shared.blacklistAppIdentifiers.append(appIdentifier!)
diff --git a/MTMR/TouchBarController.swift b/MTMR/TouchBarController.swift
index 2f70d9d..a23ebe8 100644
--- a/MTMR/TouchBarController.swift
+++ b/MTMR/TouchBarController.swift
@@ -146,7 +146,7 @@ class TouchBarController: NSObject, NSTouchBarDelegate {
     }
 
     func updateActiveApp() {
-        if frontmostApplicationIdentifier != nil && blacklistAppIdentifiers.firstIndex(of: frontmostApplicationIdentifier!) != nil {
+        if frontmostApplicationIdentifier != nil && blacklistAppIdentifiers.index(of: frontmostApplicationIdentifier!) != nil {
             dismissTouchBar()
         } else {
             presentTouchBar()
diff --git a/MTMR/Widgets/AppScrubberTouchBarItem.swift b/MTMR/Widgets/AppScrubberTouchBarItem.swift
index 46a2b8c..8d15966 100644
--- a/MTMR/Widgets/AppScrubberTouchBarItem.swift
+++ b/MTMR/Widgets/AppScrubberTouchBarItem.swift
@@ -72,7 +72,7 @@ class AppScrubberTouchBarItem: NSCustomTouchBarItem, NSScrubberDelegate, NSScrub
     func updateRunningApplication() {
         let newApplications = launchedApplications()
 
-        let index = newApplications.firstIndex {
+        let index = newApplications.index {
             $0.bundleIdentifier == frontmostApplicationIdentifier
         }
 
@@ -181,7 +181,7 @@ class AppScrubberTouchBarItem: NSCustomTouchBarItem, NSScrubberDelegate, NSScrub
             }
         } else {
             hf.tap(strong: 6)
-            if let index = self.persistentAppIdentifiers.firstIndex(of: bundleIdentifier!) {
+            if let index = self.persistentAppIdentifiers.index(of: bundleIdentifier!) {
                 persistentAppIdentifiers.remove(at: index)
             } else {
                 persistentAppIdentifiers.append(bundleIdentifier!)