diff --git a/Sources/System/FilePath/FilePathTempPosix.swift b/Sources/System/FilePath/FilePathTempPosix.swift
index 2ac7098a..fa88cfe5 100644
--- a/Sources/System/FilePath/FilePathTempPosix.swift
+++ b/Sources/System/FilePath/FilePathTempPosix.swift
@@ -12,15 +12,15 @@
 #if SYSTEM_PACKAGE_DARWIN
 import Darwin
 #elseif canImport(Glibc)
-import CSystem
+internal import CSystem
 import Glibc
 #elseif canImport(Musl)
-import CSystem
+internal import CSystem
 import Musl
 #elseif canImport(WASILibc)
 import WASILibc
 #elseif canImport(Android)
-import CSystem
+internal import CSystem
 import Android
 #else
 #error("Unsupported Platform")
diff --git a/Sources/System/FileSystem/Stat.swift b/Sources/System/FileSystem/Stat.swift
index ce4b6b5a..f1613310 100644
--- a/Sources/System/FileSystem/Stat.swift
+++ b/Sources/System/FileSystem/Stat.swift
@@ -15,15 +15,15 @@
 #if SYSTEM_PACKAGE_DARWIN
 import Darwin
 #elseif canImport(Glibc)
-import CSystem
+internal import CSystem
 import Glibc
 #elseif canImport(Musl)
-import CSystem
+internal import CSystem
 import Musl
 #elseif canImport(WASILibc)
 import WASILibc
 #elseif canImport(Android)
-import CSystem
+internal import CSystem
 import Android
 #else
 #error("Unsupported Platform")
diff --git a/Sources/System/IORing/IOCompletion.swift b/Sources/System/IORing/IOCompletion.swift
index d9e69050..87c2acd9 100644
--- a/Sources/System/IORing/IOCompletion.swift
+++ b/Sources/System/IORing/IOCompletion.swift
@@ -1,7 +1,7 @@
 #if compiler(>=6.2) && $Lifetimes
 #if os(Linux)
 
-import CSystem
+internal import CSystem
 
 public extension IORing {
     struct Completion: ~Copyable {
diff --git a/Sources/System/IORing/IORequest.swift b/Sources/System/IORing/IORequest.swift
index 4a388c49..a78ed2f5 100644
--- a/Sources/System/IORing/IORequest.swift
+++ b/Sources/System/IORing/IORequest.swift
@@ -1,7 +1,7 @@
 #if compiler(>=6.2) && $Lifetimes
 #if os(Linux)
 
-import CSystem
+internal import CSystem
 
 @usableFromInline
 internal enum IORequestCore {
diff --git a/Sources/System/IORing/IORing+Util.swift b/Sources/System/IORing/IORing+Util.swift
index be258867..d373568d 100644
--- a/Sources/System/IORing/IORing+Util.swift
+++ b/Sources/System/IORing/IORing+Util.swift
@@ -10,7 +10,7 @@
 #if compiler(>=6.2) && $Lifetimes
 #if os(Linux)
 
-import CSystem
+internal import CSystem
 #if canImport(Glibc)
 import Glibc
 #elseif canImport(Musl)
diff --git a/Sources/System/IORing/IORing.swift b/Sources/System/IORing/IORing.swift
index 27d27a0e..0346f0fc 100644
--- a/Sources/System/IORing/IORing.swift
+++ b/Sources/System/IORing/IORing.swift
@@ -1,7 +1,7 @@
 #if compiler(>=6.2) && $Lifetimes
 #if os(Linux)
 
-import CSystem
+internal import CSystem
 // needed for mmap
 #if canImport(Glibc)
 import Glibc
diff --git a/Sources/System/IORing/RawIORequest.swift b/Sources/System/IORing/RawIORequest.swift
index 40156ddc..aca0f5c8 100644
--- a/Sources/System/IORing/RawIORequest.swift
+++ b/Sources/System/IORing/RawIORequest.swift
@@ -1,7 +1,7 @@
 #if compiler(>=6.2) && $Lifetimes
 #if os(Linux)
 
-import CSystem
+internal import CSystem
 #if canImport(Glibc)
 import Glibc
 #elseif canImport(Musl)
diff --git a/Sources/System/Internals/CInterop.swift b/Sources/System/Internals/CInterop.swift
index 5570d1e0..8ef0f128 100644
--- a/Sources/System/Internals/CInterop.swift
+++ b/Sources/System/Internals/CInterop.swift
@@ -10,18 +10,18 @@
 #if SYSTEM_PACKAGE_DARWIN
 import Darwin
 #elseif os(Windows)
-import CSystem
+internal import CSystem
 import ucrt
 #elseif canImport(Glibc)
-import CSystem
+internal import CSystem
 import Glibc
 #elseif canImport(Musl)
-import CSystem
+internal import CSystem
 import Musl
 #elseif canImport(WASILibc)
 import WASILibc
 #elseif canImport(Bionic)
-import CSystem
+internal import CSystem
 import Bionic
 #else
 #error("Unsupported Platform")
diff --git a/Sources/System/Internals/Constants.swift b/Sources/System/Internals/Constants.swift
index 656e2c38..7b08d933 100644
--- a/Sources/System/Internals/Constants.swift
+++ b/Sources/System/Internals/Constants.swift
@@ -27,7 +27,11 @@ import Android
 #error("Unsupported Platform")
 #endif
 
-import CSystem
+#if os(FreeBSD)
+public import CSystem
+#else
+internal import CSystem
+#endif
 
 // MARK: errno
 #if SYSTEM_PACKAGE_DARWIN
diff --git a/Sources/System/Internals/Exports.swift b/Sources/System/Internals/Exports.swift
index 088a3251..f2e1cbc6 100644
--- a/Sources/System/Internals/Exports.swift
+++ b/Sources/System/Internals/Exports.swift
@@ -15,18 +15,18 @@
 #if SYSTEM_PACKAGE_DARWIN
 import Darwin
 #elseif os(Windows)
-import CSystem
+internal import CSystem
 import ucrt
 #elseif canImport(Glibc)
-import CSystem
+internal import CSystem
 import Glibc
 #elseif canImport(Musl)
-import CSystem
+internal import CSystem
 import Musl
 #elseif canImport(WASILibc)
 import WASILibc
 #elseif canImport(Android)
-import CSystem
+internal import CSystem
 import Android
 #else
 #error("Unsupported Platform")
diff --git a/Sources/System/Internals/Syscalls.swift b/Sources/System/Internals/Syscalls.swift
index b0d9dae1..09090299 100644
--- a/Sources/System/Internals/Syscalls.swift
+++ b/Sources/System/Internals/Syscalls.swift
@@ -7,7 +7,7 @@
  See https://swift.org/LICENSE.txt for license information
 */
 
-import CSystem
+internal import CSystem
 #if SYSTEM_PACKAGE_DARWIN
 import Darwin
 #elseif canImport(Glibc)
diff --git a/Tests/SystemTests/FileTypesTest.swift b/Tests/SystemTests/FileTypesTest.swift
index 0ddcb0de..76f99113 100644
--- a/Tests/SystemTests/FileTypesTest.swift
+++ b/Tests/SystemTests/FileTypesTest.swift
@@ -55,6 +55,15 @@ final class FileDescriptorTest: XCTestCase {
 #if SYSTEM_PACKAGE_DARWIN
     XCTAssertEqual(O_SYMLINK, FileDescriptor.OpenOptions.symlink.rawValue)
     XCTAssertEqual(O_EVTONLY, FileDescriptor.OpenOptions.eventOnly.rawValue)
+
+    if #available(macOS 27.0, iOS 27.0, watchOS 27.0, tvOS 27.0, visionOS 27.0, *) {
+      XCTAssertEqual(
+        O_CLOFORK, FileDescriptor.PipeOptions.closeOnFork.rawValue
+      )
+      XCTAssertEqual(
+        O_CLOFORK, FileDescriptor.DuplicateOptions.closeOnFork.rawValue
+      )
+    }
 #endif
 
 #if os(FreeBSD)