diff --git a/Package.swift b/Package.swift
index 8ebc98ba..4c6e4ab2 100644
--- a/Package.swift
+++ b/Package.swift
@@ -18,6 +18,7 @@ let targets: [PackageDescription.Target] = [
     dependencies: ["CSystem"],
     path: "Sources/System",
     swiftSettings: [
+      .define("SYSTEM_PACKAGE"),
       .define("ENABLE_MOCKING", .when(configuration: .debug))
     ]),
   .target(
diff --git a/Sources/System/FilePath/FilePathComponentView.swift b/Sources/System/FilePath/FilePathComponentView.swift
index 7b5394bb..5a4a8dc6 100644
--- a/Sources/System/FilePath/FilePathComponentView.swift
+++ b/Sources/System/FilePath/FilePathComponentView.swift
@@ -40,6 +40,30 @@ extension FilePath {
     }
   }
 
+  #if SYSTEM_PACKAGE
+  /// View the non-root components that make up this path.
+  public var components: ComponentView {
+    get { ComponentView(self) }
+    _modify {
+      // RRC's empty init means that we can't guarantee that the yielded
+      // view will restore our root. So copy it out first.
+      //
+      // TODO(perf): Small-form root (especially on Unix). Have Root
+      // always copy out (not worth ref counting). Make sure that we're
+      // not needlessly sliding values around or triggering a COW
+      let rootStr = self.root?._systemString ?? SystemString()
+      var comp = ComponentView(self)
+      self = FilePath()
+      defer {
+        self = comp._path
+        if root?._slice.elementsEqual(rootStr) != true {
+          self.root = Root(rootStr)
+        }
+      }
+      yield &comp
+    }
+  }
+  #else
   /// View the non-root components that make up this path.
   public var components: ComponentView {
     __consuming get { ComponentView(self) }
@@ -62,6 +86,7 @@ extension FilePath {
       yield &comp
     }
   }
+  #endif
 }
 
 // @available(macOS 9999, iOS 9999, watchOS 9999, tvOS 9999, *)
diff --git a/Sources/System/FilePath/FilePathString.swift b/Sources/System/FilePath/FilePathString.swift
index 842367c1..9f43a9c0 100644
--- a/Sources/System/FilePath/FilePathString.swift
+++ b/Sources/System/FilePath/FilePathString.swift
@@ -32,10 +32,15 @@ extension FilePath {
   /// The pointer passed as an argument to `body` is valid
   /// only during the execution of this method.
   /// Don't try to store the pointer for later use.
+  @_alwaysEmitIntoClient
   public func withPlatformString<Result>(
     _ body: (UnsafePointer<CInterop.PlatformChar>) throws -> Result
   ) rethrows -> Result {
-    try _withPlatformString(body)
+    #if !os(Windows)
+    return try withCString(body)
+    #else
+    return try _withPlatformString(body)
+    #endif
   }
 }
 
@@ -412,7 +417,7 @@ extension FilePath {
     #if os(Windows)
     fatalError("FilePath.withCString() unsupported on Windows ")
     #else
-    return try withPlatformString(body)
+    return try _withPlatformString(body)
     #endif
   }
 }
diff --git a/Sources/System/Internals/Mocking.swift b/Sources/System/Internals/Mocking.swift
index b1ca4856..4c74b6a4 100644
--- a/Sources/System/Internals/Mocking.swift
+++ b/Sources/System/Internals/Mocking.swift
@@ -146,13 +146,20 @@ private func originalSyscallName(_ function: String) -> String {
 
 private func mockImpl(
   name: String,
+  path: UnsafePointer<CChar>?,
   _ args: [AnyHashable]
 ) -> CInt {
+  precondition(mockingEnabled)
   let origName = originalSyscallName(name)
   guard let driver = currentMockingDriver else {
     fatalError("Mocking requested from non-mocking context")
   }
-  driver.trace.add(Trace.Entry(name: origName, args))
+  var mockArgs: Array<AnyHashable> = []
+  if let p = path {
+    mockArgs.append(String(_errorCorrectingPlatformString: p))
+  }
+  mockArgs.append(contentsOf: args)
+  driver.trace.add(Trace.Entry(name: origName, mockArgs))
 
   switch driver.forceErrno {
   case .none: break
@@ -170,21 +177,20 @@ private func mockImpl(
 }
 
 internal func _mock(
-  name: String = #function, _ args: AnyHashable...
+  name: String = #function, path: UnsafePointer<CChar>? = nil, _ args: AnyHashable...
 ) -> CInt {
-  precondition(mockingEnabled)
-  return mockImpl(name: name, args)
+  return mockImpl(name: name, path: path, args)
 }
 internal func _mockInt(
-  name: String = #function, _ args: AnyHashable...
+  name: String = #function, path: UnsafePointer<CChar>? = nil, _ args: AnyHashable...
 ) -> Int {
-  Int(mockImpl(name: name, args))
+  Int(mockImpl(name: name, path: path, args))
 }
 
 internal func _mockOffT(
-  name: String = #function, _ args: AnyHashable...
+  name: String = #function, path: UnsafePointer<CChar>? = nil, _ args: AnyHashable...
 ) -> _COffT {
-  _COffT(mockImpl(name: name, args))
+  _COffT(mockImpl(name: name, path: path, args))
 }
 #endif // ENABLE_MOCKING
 
diff --git a/Sources/System/Internals/Syscalls.swift b/Sources/System/Internals/Syscalls.swift
index a755928e..ecfdc843 100644
--- a/Sources/System/Internals/Syscalls.swift
+++ b/Sources/System/Internals/Syscalls.swift
@@ -26,7 +26,7 @@ internal func system_open(
 ) -> CInt {
 #if ENABLE_MOCKING
   if mockingEnabled {
-    return _mock(String(_errorCorrectingPlatformString: path), oflag)
+    return _mock(path: path, oflag)
   }
 #endif
   return open(path, oflag)
@@ -38,7 +38,7 @@ internal func system_open(
 ) -> CInt {
 #if ENABLE_MOCKING
   if mockingEnabled {
-    return _mock(String(_errorCorrectingPlatformString: path), oflag, mode)
+    return _mock(path: path, oflag, mode)
   }
 #endif
   return open(path, oflag, mode)
diff --git a/Tests/SystemTests/XCTestManifests.swift b/Tests/SystemTests/XCTestManifests.swift
index abbfe070..68eb9e82 100644
--- a/Tests/SystemTests/XCTestManifests.swift
+++ b/Tests/SystemTests/XCTestManifests.swift
@@ -17,6 +17,7 @@ extension FileDescriptorTest {
     // to regenerate.
     static let __allTests__FileDescriptorTest = [
         ("testConstants", testConstants),
+        ("testStandardDescriptors", testStandardDescriptors),
     ]
 }
 
@@ -26,6 +27,7 @@ extension FileOperationsTest {
     // to regenerate.
     static let __allTests__FileOperationsTest = [
         ("testAdHocOpen", testAdHocOpen),
+        ("testGithubIssues", testGithubIssues),
         ("testHelpers", testHelpers),
         ("testSyscalls", testSyscalls),
     ]
@@ -38,7 +40,6 @@ extension FilePathComponentsTest {
     static let __allTests__FilePathComponentsTest = [
         ("testAdHocRRC", testAdHocRRC),
         ("testCases", testCases),
-        ("testConcatenation", testConcatenation),
         ("testSeparatorNormalization", testSeparatorNormalization),
     ]
 }