diff --git a/Dockerfile b/Dockerfile
new file mode 100644
index 0000000..b668c9e
--- /dev/null
+++ b/Dockerfile
@@ -0,0 +1,6 @@
+FROM swift:4.2.1
+COPY XcodeProject.xcodeproj ./XcodeProject.xcodeproj
+COPY Package.swift ./Package.swift
+COPY Sources ./Sources
+COPY Tests ./Tests
+RUN swift test --configuration debug
diff --git a/Makefile b/Makefile
index d7b81e6..a5c3597 100644
--- a/Makefile
+++ b/Makefile
@@ -8,6 +8,9 @@ test:
 	
 xcode:
 	swift package generate-xcodeproj --xcconfig-overrides=overrides.xcconfig
+	
+linux:
+	swift test --generate-linuxmain $(SWIFTC_FLAGS)
 
 clean:
-	swift build --clean
\ No newline at end of file
+	swift build --clean
diff --git a/Package.swift b/Package.swift
index c6e1148..5f6ee0d 100644
--- a/Package.swift
+++ b/Package.swift
@@ -1,4 +1,4 @@
-// swift-tools-version:4.0
+// swift-tools-version:4.2
 // The swift-tools-version declares the minimum version of Swift required to build this package.
 
 import PackageDescription
diff --git a/Sources/XcodeProject/Objects/PBXFileType.swift b/Sources/XcodeProject/Objects/PBXFileType.swift
index 1ecf70b..785a7fa 100644
--- a/Sources/XcodeProject/Objects/PBXFileType.swift
+++ b/Sources/XcodeProject/Objects/PBXFileType.swift
@@ -7,7 +7,9 @@
 //
 
 import Foundation
+#if canImport(CoreServices)
 import CoreServices
+#endif
 
 public struct PBXFileType {
 	static var fileTypes: [PBXFileType] = [
@@ -39,8 +41,28 @@ public struct PBXFileType {
 	var isSource: Bool {
 		return UTTypeConformsTo(uniformType as CFString, kUTTypeSourceCode)
 	}
+	
+	static func fileType(filePath: String) -> PBXFileType? {
+		let fileExtension = (filePath as NSString).pathExtension
+		return fileType(fileExtension: fileExtension)
+	}
+	
+	static func fileType(reference: PBXFileReference) -> PBXFileType? {
+		return fileType(filePath: reference.fileType.type)
+	}
+}
+
+#if !canImport(CoreServices)
+typealias CFString = String
+let kUTTypeCHeader: CFString = "public.c-header"
+let kUTTypeCPlusPlusHeader: CFString = "public.c-plus-plus-header"
+let kUTTypeSourceCode: CFString = "public.source-code"
+func UTTypeConformsTo(_ inUTI: CFString, _ inConformsToUTI: CFString) -> Bool {
+	return true
 }
+#endif
 
+#if canImport(CoreServices)
 public extension PBXFileType {
 	static func fileType(fileExtension: String) -> PBXFileType? {
 		guard let uniformType = UTTypeCreatePreferredIdentifierForTag(kUTTagClassFilenameExtension, fileExtension as CFString, nil)?.takeUnretainedValue() as String? else { return nil }
@@ -48,16 +70,14 @@ public extension PBXFileType {
 			$0.uniformType == uniformType
 		}
 	}
-	
-	static func fileType(filePath: String) -> PBXFileType? {
-		let fileExtension = (filePath as NSString).pathExtension
-		return fileType(fileExtension: fileExtension)
-	}
-	
-	static func fileType(reference: PBXFileReference) -> PBXFileType? {
-		return fileType(filePath: reference.fileType.type)
+}
+#else
+public extension PBXFileType {
+	static func fileType(fileExtension: String) -> PBXFileType? {
+		return nil
 	}
 }
+#endif
 
 extension PBXFileType {
 	var buildPhaseType: PBXBuildPhase.Type? {
diff --git a/Sources/XcodeProject/Objects/PBXGlobalID+Generator.swift b/Sources/XcodeProject/Objects/PBXGlobalID+Generator.swift
index b09a52b..addf8fc 100644
--- a/Sources/XcodeProject/Objects/PBXGlobalID+Generator.swift
+++ b/Sources/XcodeProject/Objects/PBXGlobalID+Generator.swift
@@ -42,17 +42,13 @@ extension PBXGlobalID {
 		private var lastTime: UInt32 = 0
 		private var firstSequence: UInt16 = 0
 		
-		init(userName: String = NSUserName(), processId: pid_t = getpid(), random: inout RandomNumberGenerator, referenceDateGenerator: @escaping () -> Date = Generator.referenceDate) {
+		init(userName: String = NSUserName(), processId: pid_t = getpid(), hostId: UInt32, random: UInt16, referenceDateGenerator: @escaping () -> Date = Generator.referenceDate) {
 			self.referenceDateGenerator = referenceDateGenerator
 			
-			var hostId: UInt32 = UInt32(gethostid())
-			if hostId == 0 {
-				hostId = random.next()
-			}
 			self.gid = GlobalIdentifier(
 				userHash: Generator.userHash(userName: userName),
 				pidByte: UInt8(truncatingIfNeeded: processId),
-				random: random.next(),
+				random: random,
 				time: 0,
 				hostShift: UInt8(truncatingIfNeeded: (hostId >> 0x10) & 0xff),
 				hostHigh: UInt8(truncatingIfNeeded: (hostId & 0xff00) >> 0x8),
diff --git a/Sources/XcodeProject/Objects/PBXGlobalID.swift b/Sources/XcodeProject/Objects/PBXGlobalID.swift
index e60be67..6410a4f 100644
--- a/Sources/XcodeProject/Objects/PBXGlobalID.swift
+++ b/Sources/XcodeProject/Objects/PBXGlobalID.swift
@@ -27,13 +27,19 @@ public struct PBXGlobalID: RawRepresentable {
 		return strings?.compactMap { return PBXGlobalID(rawValue: $0) }
 	}
 	
-	private static var randomNumberGenerator: RandomNumberGenerator = SystemRandomNumberGenerator()
-	private static var generator: PBXGlobalID.Generator = PBXGlobalID.Generator(random: &randomNumberGenerator)
+	private static var generator: PBXGlobalID.Generator = {
+		var randomNumberGenerator: RandomNumberGenerator = SystemRandomNumberGenerator()
+		var hostId: UInt32 = UInt32(gethostid())
+		if hostId == 0 {
+			hostId = randomNumberGenerator.next()
+		}
+		return PBXGlobalID.Generator(hostId: hostId, random: randomNumberGenerator.next())
+	}()
 }
 
 extension PBXGlobalID: Hashable {
-	public var hashValue: Int {
-		return rawValue.hashValue
+	public func hash(into hasher: inout Hasher) {
+		hasher.combine(rawValue)
 	}
 	
 	public static func ==(lhs: PBXGlobalID, rhs: PBXGlobalID) -> Bool {
diff --git a/Sources/XcodeProject/Objects/PBXObject.swift b/Sources/XcodeProject/Objects/PBXObject.swift
index fb5c8ae..58780a0 100644
--- a/Sources/XcodeProject/Objects/PBXObject.swift
+++ b/Sources/XcodeProject/Objects/PBXObject.swift
@@ -67,8 +67,8 @@ public class PBXObject {
 }
 
 extension PBXObject: Hashable {
-	public var hashValue: Int {
-		return globalID.hashValue
+	public func hash(into hasher: inout Hasher) {
+		hasher.combine(globalID)
 	}
 	
 	public static func ==(lhs: PBXObject, rhs: PBXObject) -> Bool {
diff --git a/Sources/XcodeProject/Objects/References/PBXReference.swift b/Sources/XcodeProject/Objects/References/PBXReference.swift
index e71917b..4b6e9b9 100644
--- a/Sources/XcodeProject/Objects/References/PBXReference.swift
+++ b/Sources/XcodeProject/Objects/References/PBXReference.swift
@@ -33,14 +33,30 @@ public class PBXReference: PBXObject {
 	var indentWidth: Int?
 	
 	var buildFiles: [PBXBuildFile] {
-		return _buildFiles.allObjects
+		return _buildFiles.compactMap { $0.item }
 	}
-	private var _buildFiles = NSHashTable<PBXBuildFile>.weakObjects()
+	
+	private struct WeakBuildFile: Hashable {
+		weak var item: PBXBuildFile?
+		
+		static func ==(lhs: WeakBuildFile, rhs: WeakBuildFile) -> Bool {
+			return lhs.item == rhs.item
+		}
+		
+		func hash(into hasher: inout Hasher) {
+			hasher.combine(item)
+		}
+	}
+	
+	private var _buildFiles: Array<WeakBuildFile> = []
+	
 	func register(buildFile: PBXBuildFile) {
-		_buildFiles.add(buildFile)
+		_buildFiles.removeAll { $0.item == nil }
+		_buildFiles.append(WeakBuildFile(item: buildFile))
 	}
+	
 	func unregister(buildFile: PBXBuildFile) {
-		_buildFiles.remove(buildFile)
+		_buildFiles.removeAll { $0.item == nil || $0.item == buildFile }
 	}
 	
 	public var displayName: String {
diff --git a/Sources/XcodeProject/ProjectFile.swift b/Sources/XcodeProject/ProjectFile.swift
index 3480ff7..eb75129 100644
--- a/Sources/XcodeProject/ProjectFile.swift
+++ b/Sources/XcodeProject/ProjectFile.swift
@@ -39,7 +39,6 @@ public final class ProjectFile {
 	public private(set) var project: PBXProject
 	
 	let url: URL
-	let fileWrapper: FileWrapper
 	
 	/// Initializes a new project file from the given URL
 	///
@@ -47,18 +46,8 @@ public final class ProjectFile {
 	/// - Returns: A fully parsed project from the provided source or `nil` if an error happened
 	public init(url: URL) throws {
 		self.url = url
-		self.fileWrapper = try FileWrapper(url: url, options: [])
-		guard fileWrapper.isDirectory else {
-			throw CocoaError.error(.fileReadUnknown)
-		}
-		
-		guard let pbxproj = fileWrapper.fileWrappers?["project.pbxproj"], pbxproj.isRegularFile else {
-			throw CocoaError.error(.fileReadUnknown)
-		}
-		
-		guard let data = pbxproj.regularFileContents else {
-			throw Error.invalid
-		}
+		let pbxproj = URL(fileURLWithPath: "project.pbxproj", relativeTo: url)
+		let data = try Data(contentsOf: pbxproj)
 
 		guard let plist = try PropertyListSerialization.propertyList(from: data, options: [], format: nil) as? [String: Any] else {
 			throw Error.invalidPlist
@@ -85,23 +74,6 @@ public final class ProjectFile {
 		project.path = url.path
 		self.project = project
 	}
-	
-	public func currentFileWrapper() throws -> FileWrapper {
-		let currentFileWrapper = fileWrapper
-		
-		let oldPbxproj = currentFileWrapper.fileWrappers!["project.pbxproj"]!
-		
-		let dataStream = DataStreamWriter()
-		let archiver = PBXPListArchiver(projectFile: self)
-		try archiver.write(stream: dataStream)
-		let newPbxproj = FileWrapper(regularFileWithContents: dataStream.data)
-		newPbxproj.preferredFilename = "project.pbxproj"
-		
-		currentFileWrapper.removeFileWrapper(oldPbxproj)
-		currentFileWrapper.addFileWrapper(newPbxproj)
-		
-		return currentFileWrapper
-	}
 }
 
 extension ProjectFile {
@@ -112,19 +84,10 @@ extension ProjectFile {
 	public func save(to destination: URL? = nil) throws {
 		let destination = destination ?? url
 		
-		guard let oldPbxproj = fileWrapper.fileWrappers?["project.pbxproj"], oldPbxproj.isRegularFile else {
-			throw CocoaError.error(.fileReadUnknown)
-		}
-		
 		let dataStream = DataStreamWriter()
 		let archiver = PBXPListArchiver(projectFile: self)
 		try archiver.write(stream: dataStream)
-		let newPbxproj = FileWrapper(regularFileWithContents: dataStream.data)
-		newPbxproj.preferredFilename = "project.pbxproj"
-		
-		fileWrapper.removeFileWrapper(oldPbxproj)
-		fileWrapper.addFileWrapper(newPbxproj)
-		
-		try fileWrapper.write(to: destination, options: [.atomic], originalContentsURL: nil)
+		let pbxprojURL = URL(fileURLWithPath: "project.pbxproj", relativeTo: destination)
+		try dataStream.data.write(to: pbxprojURL, options: [.atomic])
 	}
 }
diff --git a/Sources/XcodeProject/Workspace.swift b/Sources/XcodeProject/Workspace.swift
index 1303c14..9a91e05 100644
--- a/Sources/XcodeProject/Workspace.swift
+++ b/Sources/XcodeProject/Workspace.swift
@@ -61,7 +61,6 @@ public final class Workspace: WorkspaceReference {
 	}
 	let url: URL
 	public var referenceURL: URL? { return url.deletingLastPathComponent() }
-	public let fileWrapper: FileWrapper
 	public var references: [WorkspaceItem] = []
 	
 	public class FileReference: WorkspaceItem {
@@ -88,15 +87,8 @@ public final class Workspace: WorkspaceReference {
 	
 	public init(url: URL) throws {
 		self.url = url
-		self.fileWrapper = try FileWrapper(url: url, options: [])
-		if fileWrapper.isDirectory == false {
-			//throw
-		}
-		
-		guard let workspaceData = fileWrapper.fileWrappers?["contents.xcworkspacedata"], workspaceData.isRegularFile,
-			let data = workspaceData.regularFileContents else {
-				throw Error.invalid
-		}
+		let workspaceFileURL = URL(fileURLWithPath: "contents.xcworkspacedata", relativeTo: url)
+		let data = try Data(contentsOf: workspaceFileURL)
 		
 		let document = try XMLDocument(data: data, options: [])
 		guard let children = document.rootElement()?.children as? [XMLElement] else { throw Error.invalid }
diff --git a/Tests/LinuxMain.swift b/Tests/LinuxMain.swift
new file mode 100644
index 0000000..1a0c95c
--- /dev/null
+++ b/Tests/LinuxMain.swift
@@ -0,0 +1,8 @@
+import XCTest
+
+import XcodeProjectTests
+
+var tests = [XCTestCaseEntry]()
+tests += XcodeProjectTests.__allTests()
+
+XCTMain(tests)
diff --git a/Tests/XcodeProjectTests/PBXGlobalIDTests.swift b/Tests/XcodeProjectTests/PBXGlobalIDTests.swift
index 45c6685..c69af45 100644
--- a/Tests/XcodeProjectTests/PBXGlobalIDTests.swift
+++ b/Tests/XcodeProjectTests/PBXGlobalIDTests.swift
@@ -10,14 +10,6 @@ import XCTest
 @testable import XcodeProject
 
 class PBXGlobalIDTests: XCTestCase {
-	struct FakeRandomGenerator: RandomNumberGenerator {
-		private var value: UInt64 = 1234567890
-		mutating func next() -> UInt64 {
-			defer { value += 1 }
-			return value
-		}
-	}
-	
 	func mockDateGenerator() -> Date {
 		let components = DateComponents(timeZone: TimeZone(secondsFromGMT: 0), year: 2014, month: 07, day: 29, hour: 17, minute: 04, second: 20)
 		let date = Calendar(identifier: .gregorian).date(from: components)
@@ -25,9 +17,7 @@ class PBXGlobalIDTests: XCTestCase {
 	}
 	
     func testIDGeneration() {
-		let processId: pid_t = 50_000
-		var randomNumberGenerator: RandomNumberGenerator = FakeRandomGenerator()
-		var generator = PBXGlobalID.Generator(userName: "XcodeProject", processId: processId, random: &randomNumberGenerator, referenceDateGenerator: mockDateGenerator)
+		var generator = PBXGlobalID.Generator(userName: "XcodeProject", processId: 50_000, hostId: 1234567890, random: 723, referenceDateGenerator: mockDateGenerator)
 		XCTAssertEqual("8C5002D419880B94009602D2", generator.next())
 		XCTAssertEqual("8C5002D519880B94009602D2", generator.next())
 		XCTAssertEqual("8C5002D619880B94009602D2", generator.next())
diff --git a/Tests/XcodeProjectTests/XCTestManifests.swift b/Tests/XcodeProjectTests/XCTestManifests.swift
new file mode 100644
index 0000000..364f0b7
--- /dev/null
+++ b/Tests/XcodeProjectTests/XCTestManifests.swift
@@ -0,0 +1,25 @@
+import XCTest
+
+extension PBXGlobalIDTests {
+    static let __allTests = [
+        ("testIDGeneration", testIDGeneration),
+    ]
+}
+
+extension XcodeProjectTests {
+    static let __allTests = [
+        ("testAggregateTarget", testAggregateTarget),
+        ("testPrivateProjectFolder", testPrivateProjectFolder),
+        ("testSelfArchive", testSelfArchive),
+        ("testSelfSave", testSelfSave),
+    ]
+}
+
+#if !os(macOS)
+public func __allTests() -> [XCTestCaseEntry] {
+    return [
+        testCase(PBXGlobalIDTests.__allTests),
+        testCase(XcodeProjectTests.__allTests),
+    ]
+}
+#endif
diff --git a/Tests/XcodeProjectTests/XcodeProjectTests.swift b/Tests/XcodeProjectTests/XcodeProjectTests.swift
index 3fe64ea..2744a63 100644
--- a/Tests/XcodeProjectTests/XcodeProjectTests.swift
+++ b/Tests/XcodeProjectTests/XcodeProjectTests.swift
@@ -21,27 +21,19 @@ class XcodeProjectTests: XCTestCase {
 	
 	private var selfPath: URL {
 		let fileURL = URL(fileURLWithPath: #file)
-		let projectURL = URL(fileURLWithPath: "../../XcodeProject.xcodeproj", isDirectory: true, relativeTo: fileURL).standardizedFileURL
+		let projectURL = URL(fileURLWithPath: "../../XcodeProject.xcodeproj/", isDirectory: true, relativeTo: fileURL).standardizedFileURL
 		return projectURL
 	}
 	
 	@inline(__always)
 	func assertReadWriteProject(url: URL) throws {
-		guard let projectFile = try? ProjectFile(url: url) else {
-			XCTFail("Failed to create ProjectFile")
-			return
-		}
-		
+		let projectFile = try ProjectFile(url: url)
 		let archiver = PBXPListArchiver(projectFile: projectFile)
 		let streamWriter = StringStreamWriter()
-		do {
-			try archiver.write(stream: streamWriter)
-		} catch {
-			XCTFail("Archiver write failed")
-		}
+		try archiver.write(stream: streamWriter)
 		
 		let url = URL(fileURLWithPath: "project.pbxproj", relativeTo: projectFile.url)
-		let data = try! Data(contentsOf: url)
+		let data = try Data(contentsOf: url)
 		let string = String(data: data, encoding: .utf8)
 		
 		if streamWriter.string != string {
@@ -57,17 +49,12 @@ class XcodeProjectTests: XCTestCase {
 		//try assertReadWriteProject(url: selfPath)
 	}
 	
-	func testSelfSave() {
-		let copiedProjectURL = URL(fileURLWithPath: "\(NSTemporaryDirectory())\(UUID().uuidString).xcodeproj")
-		
-		do {
-			try FileManager.default.copyItem(at: selfPath, to: copiedProjectURL)
-			let projectFile = try ProjectFile(url: copiedProjectURL)
-			projectFile.project.mainGroup.sort(recursive: true, by: .type)
-			try projectFile.save()
-		} catch (let error) {
-			XCTFail(error.localizedDescription)
-		}
+	func testSelfSave() throws {
+		let copiedProjectURL = URL(fileURLWithPath: "\(NSTemporaryDirectory())\(UUID().uuidString).xcodeproj", isDirectory: true)
+		try FileManager.default.copyItem(at: selfPath, to: copiedProjectURL)
+		let projectFile = try ProjectFile(url: copiedProjectURL)
+		projectFile.project.mainGroup.sort(recursive: true, by: .type)
+		try projectFile.save()
 	}
 	
 	func testAggregateTarget() throws {
@@ -77,13 +64,9 @@ class XcodeProjectTests: XCTestCase {
 	func testPrivateProjectFolder() throws {
 		guard let path = ProcessInfo.processInfo.environment["PRIVATE_PROJECTS"], !path.isEmpty else { return }
 		let privateProjectsDir = URL(fileURLWithPath: path, isDirectory: true)
-		do {
-			let files = try FileManager.default.contentsOfDirectory(at: privateProjectsDir, includingPropertiesForKeys: nil)
-			try files.filter { return $0.pathExtension == "xcodeproj" }.forEach {
-				try assertReadWriteProject(url: $0)
-			}
-		} catch {
-			XCTFail()
+		let files = try FileManager.default.contentsOfDirectory(at: privateProjectsDir, includingPropertiesForKeys: nil)
+		try files.filter { return $0.pathExtension == "xcodeproj" }.forEach {
+			try assertReadWriteProject(url: $0)
 		}
 	}
 }
diff --git a/XcodeProject.xcodeproj/project.pbxproj b/XcodeProject.xcodeproj/project.pbxproj
index 58a5dbe..251117f 100644
--- a/XcodeProject.xcodeproj/project.pbxproj
+++ b/XcodeProject.xcodeproj/project.pbxproj
@@ -7,7 +7,6 @@
 	objects = {
 
 /* Begin PBXBuildFile section */
-		6C2643E01E11C0E50057CFA4 /* GameplayKit.framework in Frameworks */ = {isa = PBXBuildFile; fileRef = 6C2643DF1E11C0E50057CFA4 /* GameplayKit.framework */; };
 		6C2643E21E11C16A0057CFA4 /* Foundation.framework in Frameworks */ = {isa = PBXBuildFile; fileRef = 6C2643E11E11C16A0057CFA4 /* Foundation.framework */; };
 		6C2644091E11C80A0057CFA4 /* PBXPListArchiver.swift in Sources */ = {isa = PBXBuildFile; fileRef = 6C2643E51E11C80A0057CFA4 /* PBXPListArchiver.swift */; };
 		6C26440A1E11C80A0057CFA4 /* PBXPListUnarchiver.swift in Sources */ = {isa = PBXBuildFile; fileRef = 6C2643E61E11C80A0057CFA4 /* PBXPListUnarchiver.swift */; };
@@ -118,7 +117,6 @@
 			buildActionMask = 2147483647;
 			files = (
 				6C2643E21E11C16A0057CFA4 /* Foundation.framework in Frameworks */,
-				6C2643E01E11C0E50057CFA4 /* GameplayKit.framework in Frameworks */,
 			);
 			runOnlyForDeploymentPostprocessing = 0;
 		};