diff --git a/CHANGELOG.md b/CHANGELOG.md
index feb64d1..1e7f1de 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,8 +1,6 @@
 # 0.20.0 (30 Sep 2023)
 
-This release adds a temporary fix for macOS 14 Sonoma + Xcode 15.
-- On macOS Sonoma the default toolchain is a 5.9-SNAPSHOT.
-- On other hosts the default toolchain continues to be 5.8-RELEASE.
+This release adds SwiftWasm 5.9 toolchain support.
 
 # 0.19.1 (9 May 2023)
 
diff --git a/Package.swift b/Package.swift
index 30c4834..55c50ec 100644
--- a/Package.swift
+++ b/Package.swift
@@ -21,7 +21,7 @@ let package = Package(
     ),
     .package(
       url: "https://github.com/apple/swift-argument-parser.git",
-      .upToNextMinor(from: "1.2.2")
+      .upToNextMinor(from: "1.2.3")
     ),
     .package(url: "https://github.com/apple/swift-nio.git", from: "2.34.0"),
     .package(
diff --git a/Sources/CartonHelpers/Async.swift b/Sources/CartonHelpers/Async.swift
index 0c42356..4f1f463 100644
--- a/Sources/CartonHelpers/Async.swift
+++ b/Sources/CartonHelpers/Async.swift
@@ -29,17 +29,11 @@ extension Sequence {
 }
 
 /// A type that can be executed as part of a nested tree of commands.
-#if swift(<5.9)
-public protocol AsyncParsableCommand: ParsableCommand {
-  mutating func run() async throws
-}
-#else
 extension AsyncParsableCommand {
   public mutating func run() throws {
     throw CleanExit.helpRequest(self)
   }
 }
-#endif
 
 public protocol AsyncMain {
   associatedtype Command: ParsableCommand
diff --git a/Sources/SwiftToolchain/Toolchain.swift b/Sources/SwiftToolchain/Toolchain.swift
index e7999b3..d79510d 100644
--- a/Sources/SwiftToolchain/Toolchain.swift
+++ b/Sources/SwiftToolchain/Toolchain.swift
@@ -212,13 +212,8 @@ public final class Toolchain {
         switch target.type {
         case .regular, .executable:
           return RelativePath("Sources").appending(component: target.name).pathString
-        #if swift(>=5.9)
         case .test, .system, .binary, .macro, .plugin:
           return nil
-        #else
-        case .test, .system, .binary, .plugin:
-          return nil
-        #endif
         }
       }
       return path