diff --git a/Sources/ArgumentParser/CMakeLists.txt b/Sources/ArgumentParser/CMakeLists.txt
index 25022c0f..ea7d83f9 100644
--- a/Sources/ArgumentParser/CMakeLists.txt
+++ b/Sources/ArgumentParser/CMakeLists.txt
@@ -46,6 +46,7 @@ add_library(ArgumentParser
   Utilities/Platform.swift
   Utilities/SequenceExtensions.swift
   Utilities/StringExtensions.swift
+  Utilities/SwiftExtensions.swift
   Utilities/Tree.swift
   
   Validators/CodingKeyValidator.swift
diff --git a/Sources/ArgumentParser/Parsable Types/ExpressibleByArgument.swift b/Sources/ArgumentParser/Parsable Types/ExpressibleByArgument.swift
index 33d81e19..0f09b90a 100644
--- a/Sources/ArgumentParser/Parsable Types/ExpressibleByArgument.swift	
+++ b/Sources/ArgumentParser/Parsable Types/ExpressibleByArgument.swift	
@@ -10,7 +10,7 @@
 //===----------------------------------------------------------------------===//
 
 /// A type that can be expressed as a command-line argument.
-public protocol ExpressibleByArgument {
+public protocol ExpressibleByArgument: _SendableMetatype {
   /// Creates a new instance of this type from a command-line-specified
   /// argument.
   init?(argument: String)
diff --git a/Sources/ArgumentParser/Parsable Types/ParsableArguments.swift b/Sources/ArgumentParser/Parsable Types/ParsableArguments.swift
index 7a476999..1154d627 100644
--- a/Sources/ArgumentParser/Parsable Types/ParsableArguments.swift	
+++ b/Sources/ArgumentParser/Parsable Types/ParsableArguments.swift	
@@ -13,7 +13,7 @@
 ///
 /// When you implement a `ParsableArguments` type, all properties must be declared with
 /// one of the four property wrappers provided by the `ArgumentParser` library.
-public protocol ParsableArguments: Decodable {
+public protocol ParsableArguments: Decodable, _SendableMetatype {
   /// Creates an instance of this parsable type using the definitions
   /// given by each property's wrapper.
   init()
diff --git a/Sources/ArgumentParser/Utilities/SwiftExtensions.swift b/Sources/ArgumentParser/Utilities/SwiftExtensions.swift
new file mode 100644
index 00000000..b09403bf
--- /dev/null
+++ b/Sources/ArgumentParser/Utilities/SwiftExtensions.swift
@@ -0,0 +1,17 @@
+//===----------------------------------------------------------------------===//
+//
+// This source file is part of the Swift Argument Parser open source project
+//
+// Copyright (c) 2020 Apple Inc. and the Swift project authors
+// Licensed under Apache License v2.0 with Runtime Library Exception
+//
+// See https://swift.org/LICENSE.txt for license information
+//
+//===----------------------------------------------------------------------===//
+
+#if compiler(>=6.2)
+/// Designates a type as having a sendable metatype.
+public protocol _SendableMetatype: SendableMetatype {}
+#else
+public protocol _SendableMetatype {}
+#endif
diff --git a/Tests/ArgumentParserEndToEndTests/CustomParsingEndToEndTests.swift b/Tests/ArgumentParserEndToEndTests/CustomParsingEndToEndTests.swift
index fe2e2a16..62d0d59d 100644
--- a/Tests/ArgumentParserEndToEndTests/CustomParsingEndToEndTests.swift
+++ b/Tests/ArgumentParserEndToEndTests/CustomParsingEndToEndTests.swift
@@ -35,10 +35,11 @@ extension Array where Element == Name {
 // MARK: -
 
 private struct Foo: ParsableCommand {
-  enum Subgroup: Equatable {
+  enum Subgroup: Equatable, Sendable {
     case first(Int)
     case second(Int)
 
+    @Sendable
     static func makeFirst(_ str: String) throws -> Subgroup {
       guard let value = Int(str) else {
         throw ValidationError("Not a valid integer for 'first'")
@@ -46,6 +47,7 @@ private struct Foo: ParsableCommand {
       return .first(value)
     }
 
+    @Sendable
     static func makeSecond(_ str: String) throws -> Subgroup {
       guard let value = Int(str) else {
         throw ValidationError("Not a valid integer for 'second'")
diff --git a/Tests/ArgumentParserUnitTests/HelpGenerationTests.swift b/Tests/ArgumentParserUnitTests/HelpGenerationTests.swift
index c414941b..19883493 100644
--- a/Tests/ArgumentParserUnitTests/HelpGenerationTests.swift
+++ b/Tests/ArgumentParserUnitTests/HelpGenerationTests.swift
@@ -148,6 +148,8 @@ extension HelpGenerationTests {
   enum OptionFlags: String, EnumerableFlag { case optional, required }
   enum Degree {
     case bachelor, graduate, doctorate
+
+    @Sendable
     static func degreeTransform(_ string: String) throws -> Degree {
       switch string {
       case "bachelor":
diff --git a/Tests/ArgumentParserUnitTests/UsageGenerationTests.swift b/Tests/ArgumentParserUnitTests/UsageGenerationTests.swift
index 99d23f1e..d7cfae89 100644
--- a/Tests/ArgumentParserUnitTests/UsageGenerationTests.swift
+++ b/Tests/ArgumentParserUnitTests/UsageGenerationTests.swift
@@ -132,6 +132,7 @@ extension UsageGenerationTests {
     enum Color {
       case red, blue
 
+      @Sendable
       static func transform(_ string: String) throws -> Color {
         switch string {
         case "red":