diff --git a/CHANGELOG.md b/CHANGELOG.md
index d7edd949..da6e686b 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -4,10 +4,12 @@
 
 #### Fixed
 - Validate scheme test action and test coverage target references before generating. [#775](https://github.com/yonaskolb/XcodeGen/pull/775) @liamnichols
+- Fixed parsing prerelease identifiers in Swift package versions [#779](https://github.com/yonaskolb/XcodeGen/pull/779) @yonaskolb
 - Fixed using legacy targets as dependencies [#778](https://github.com/yonaskolb/XcodeGen/pull/778) @yonaskolb
 
 #### Internal
 - Updated to XcodeProj 7.8.0 [#777](https://github.com/yonaskolb/XcodeGen/pull/777) @yonaskolb
+- Use https://github.com/mxcl/Version [#779](https://github.com/yonaskolb/XcodeGen/pull/779) @yonaskolb
 
 ## 2.13.0
 
diff --git a/Package.resolved b/Package.resolved
index 9d13079f..257847a0 100644
--- a/Package.resolved
+++ b/Package.resolved
@@ -55,6 +55,15 @@
           "version": "6.0.1"
         }
       },
+      {
+        "package": "Version",
+        "repositoryURL": "https://github.com/mxcl/Version",
+        "state": {
+          "branch": null,
+          "revision": "a94b48f36763c05629fc102837398505032dead9",
+          "version": "2.0.0"
+        }
+      },
       {
         "package": "XcodeProj",
         "repositoryURL": "https://github.com/tuist/XcodeProj.git",
diff --git a/Package.swift b/Package.swift
index e46baab2..1ff8fc24 100644
--- a/Package.swift
+++ b/Package.swift
@@ -18,10 +18,12 @@ let package = Package(
         .package(url: "https://github.com/onevcat/Rainbow.git", from: "3.0.0"),
         .package(url: "https://github.com/tuist/XcodeProj.git", .exact("7.8.0")),
         .package(url: "https://github.com/jakeheis/SwiftCLI.git", from: "6.0.0"),
+        .package(url: "https://github.com/mxcl/Version", from: "2.0.0"),
     ],
     targets: [
         .target(name: "XcodeGen", dependencies: [
             "XcodeGenCLI",
+            "Version",
         ]),
         .target(name: "XcodeGenCLI", dependencies: [
             "XcodeGenKit",
@@ -29,6 +31,7 @@ let package = Package(
             "SwiftCLI",
             "Rainbow",
             "PathKit",
+            "Version",
         ]),
         .target(name: "XcodeGenKit", dependencies: [
             "ProjectSpec",
@@ -42,6 +45,7 @@ let package = Package(
             "XcodeProj",
             "Yams",
             "Core",
+            "Version",
         ]),
         .target(name: "Core", dependencies: [
             "PathKit",
diff --git a/Sources/ProjectSpec/CacheFile.swift b/Sources/ProjectSpec/CacheFile.swift
index 4f055171..10e21afd 100644
--- a/Sources/ProjectSpec/CacheFile.swift
+++ b/Sources/ProjectSpec/CacheFile.swift
@@ -1,5 +1,6 @@
 import Foundation
 import Core
+import Version
 
 public class CacheFile {
 
diff --git a/Sources/ProjectSpec/DeploymentTarget.swift b/Sources/ProjectSpec/DeploymentTarget.swift
index f75fdd0b..95838031 100644
--- a/Sources/ProjectSpec/DeploymentTarget.swift
+++ b/Sources/ProjectSpec/DeploymentTarget.swift
@@ -1,5 +1,6 @@
 import Foundation
 import JSONUtilities
+import Version
 
 public struct DeploymentTarget: Equatable {
 
@@ -65,9 +66,9 @@ extension DeploymentTarget: JSONObjectConvertible {
 
         func parseVersion(_ platform: String) throws -> Version? {
             if let string: String = jsonDictionary.json(atKeyPath: .key(platform)) {
-                return try Version(string)
+                return try Version.parse(string)
             } else if let double: Double = jsonDictionary.json(atKeyPath: .key(platform)) {
-                return try Version(double)
+                return try Version.parse(double)
             } else {
                 return nil
             }
@@ -82,10 +83,10 @@ extension DeploymentTarget: JSONObjectConvertible {
 extension DeploymentTarget: JSONEncodable {
     public func toJSONValue() -> Any {
         [
-            "iOS": iOS?.string,
-            "tvOS": tvOS?.string,
-            "watchOS": watchOS?.string,
-            "macOS": macOS?.string,
+            "iOS": iOS?.description,
+            "tvOS": tvOS?.description,
+            "watchOS": watchOS?.description,
+            "macOS": macOS?.description,
         ]
     }
 }
diff --git a/Sources/ProjectSpec/SpecLoader.swift b/Sources/ProjectSpec/SpecLoader.swift
index b4fc4675..2385c2b8 100644
--- a/Sources/ProjectSpec/SpecLoader.swift
+++ b/Sources/ProjectSpec/SpecLoader.swift
@@ -3,6 +3,7 @@ import JSONUtilities
 import PathKit
 import XcodeProj
 import Yams
+import Version
 
 public class SpecLoader {
 
diff --git a/Sources/ProjectSpec/SpecOptions.swift b/Sources/ProjectSpec/SpecOptions.swift
index 5229b740..ecb14adf 100644
--- a/Sources/ProjectSpec/SpecOptions.swift
+++ b/Sources/ProjectSpec/SpecOptions.swift
@@ -1,5 +1,6 @@
 import Foundation
 import JSONUtilities
+import Version
 
 public struct SpecOptions: Equatable {
     public static let settingPresetsDefault = SettingPresets.all
@@ -118,7 +119,7 @@ extension SpecOptions: JSONObjectConvertible {
 
     public init(jsonDictionary: JSONDictionary) throws {
         if let string: String = jsonDictionary.json(atKeyPath: "minimumXcodeGenVersion") {
-            minimumXcodeGenVersion = try Version(string)
+            minimumXcodeGenVersion = try Version.parse(string)
         }
 
         carthageBuildPath = jsonDictionary.json(atKeyPath: "carthageBuildPath")
@@ -151,7 +152,7 @@ extension SpecOptions: JSONEncodable {
             "transitivelyLinkDependencies": transitivelyLinkDependencies,
             "groupSortPosition": groupSortPosition.rawValue,
             "disabledValidations": disabledValidations.map { $0.rawValue },
-            "minimumXcodeGenVersion": minimumXcodeGenVersion?.string,
+            "minimumXcodeGenVersion": minimumXcodeGenVersion?.description,
             "carthageBuildPath": carthageBuildPath,
             "carthageExecutablePath": carthageExecutablePath,
             "bundleIdPrefix": bundleIdPrefix,
diff --git a/Sources/ProjectSpec/SpecValidation.swift b/Sources/ProjectSpec/SpecValidation.swift
index 4d4e5849..ba5741ef 100644
--- a/Sources/ProjectSpec/SpecValidation.swift
+++ b/Sources/ProjectSpec/SpecValidation.swift
@@ -1,6 +1,7 @@
 import Foundation
 import JSONUtilities
 import PathKit
+import Version
 
 extension Project {
 
diff --git a/Sources/ProjectSpec/SpecValidationError.swift b/Sources/ProjectSpec/SpecValidationError.swift
index 8011fca8..c1948652 100644
--- a/Sources/ProjectSpec/SpecValidationError.swift
+++ b/Sources/ProjectSpec/SpecValidationError.swift
@@ -1,4 +1,5 @@
 import Foundation
+import Version
 
 public struct SpecValidationError: Error, CustomStringConvertible {
 
diff --git a/Sources/ProjectSpec/SwiftPackage.swift b/Sources/ProjectSpec/SwiftPackage.swift
index 7aee8575..b8447136 100644
--- a/Sources/ProjectSpec/SwiftPackage.swift
+++ b/Sources/ProjectSpec/SwiftPackage.swift
@@ -1,6 +1,7 @@
 import Foundation
 import XcodeProj
 import JSONUtilities
+import Version
 
 public struct SwiftPackage: Equatable {
 
@@ -27,17 +28,17 @@ extension SwiftPackage: JSONObjectConvertible {
         switch versionRequirement {
 
         case .upToNextMajorVersion(let version):
-            try _ = Version(version)
+            try _ = Version.parse(version)
 
         case .upToNextMinorVersion(let version):
-            try _ = Version(version)
+            try _ = Version.parse(version)
 
         case .range(let from, let to):
-            try _ = Version(from)
-            try _ = Version(to)
+            try _ = Version.parse(from)
+            try _ = Version.parse(to)
 
         case .exact(let version):
-            try _ = Version(version)
+            try _ = Version.parse(version)
 
         default:
             break
diff --git a/Sources/ProjectSpec/Target.swift b/Sources/ProjectSpec/Target.swift
index e28e33c3..d5a5e1fe 100644
--- a/Sources/ProjectSpec/Target.swift
+++ b/Sources/ProjectSpec/Target.swift
@@ -1,6 +1,7 @@
 import Foundation
 import JSONUtilities
 import XcodeProj
+import Version
 
 public struct LegacyTarget: Equatable {
     public static let passSettingsDefault = false
@@ -257,9 +258,9 @@ extension Target: NamedJSONDictionaryConvertible {
         }
 
         if let string: String = jsonDictionary.json(atKeyPath: "deploymentTarget") {
-            deploymentTarget = try Version(string)
+            deploymentTarget = try Version.parse(string)
         } else if let double: Double = jsonDictionary.json(atKeyPath: "deploymentTarget") {
-            deploymentTarget = try Version(double)
+            deploymentTarget = try Version.parse(String(double))
         } else {
             deploymentTarget = nil
         }
diff --git a/Sources/ProjectSpec/Version.swift b/Sources/ProjectSpec/Version.swift
deleted file mode 100644
index cfd2914c..00000000
--- a/Sources/ProjectSpec/Version.swift
+++ /dev/null
@@ -1,65 +0,0 @@
-import Foundation
-
-public struct Version: CustomStringConvertible, Equatable, Comparable, ExpressibleByStringLiteral {
-
-    public var major: UInt
-    public var minor: UInt
-    public var patch: UInt
-
-    public init(stringLiteral value: String) {
-        try! self.init(value)
-    }
-
-    public init(_ string: String) throws {
-        let components = try string.split(separator: ".").map { (componentString) -> UInt in
-            guard let uint = UInt(componentString) else {
-                throw SpecParsingError.invalidVersion(string)
-            }
-            return uint
-        }
-
-        guard components.count <= 3 else {
-            throw SpecParsingError.invalidVersion(string)
-        }
-
-        major = components[0]
-        minor = (components.count >= 2) ? components[1] : 0
-        patch = (components.count == 3) ? components[2] : 0
-    }
-
-    public init(_ double: Double) throws {
-        try self.init(String(double))
-    }
-
-    public init(major: UInt, minor: UInt? = 0, patch: UInt? = 0) {
-        self.major = major
-        self.minor = minor ?? 0
-        self.patch = patch ?? 0
-    }
-
-    public var string: String {
-        "\(major).\(minor).\(patch)"
-    }
-
-    public var description: String {
-        string
-    }
-
-    public func bumpingMajor() -> Version {
-        Version(major: major + 1, minor: 0, patch: 0)
-    }
-
-    public func bumpingMinor() -> Version {
-        Version(major: major, minor: minor + 1, patch: 0)
-    }
-
-    public func bumpingPatch() -> Version {
-        Version(major: major, minor: minor, patch: patch + 1)
-    }
-
-    public static func < (lhs: Version, rhs: Version) -> Bool {
-        guard lhs.major == rhs.major else { return lhs.major < rhs.major }
-        guard lhs.minor == rhs.minor else { return lhs.minor < rhs.minor }
-        return lhs.patch < rhs.patch
-    }
-}
diff --git a/Sources/ProjectSpec/VersionExtensions.swift b/Sources/ProjectSpec/VersionExtensions.swift
new file mode 100644
index 00000000..010db80a
--- /dev/null
+++ b/Sources/ProjectSpec/VersionExtensions.swift
@@ -0,0 +1,28 @@
+//
+//  File.swift
+//  
+//
+//  Created by Yonas Kolb on 7/2/20.
+//
+
+import Foundation
+import Version
+
+extension Version: ExpressibleByStringLiteral {
+
+    public static func parse(_ string: String) throws -> Version {
+        if let version = Version(tolerant: string) {
+            return version
+        } else {
+            throw SpecParsingError.invalidVersion(string)
+        }
+    }
+
+    public static func parse(_ double: Double) throws -> Version {
+        return try Version.parse(String(double))
+    }
+
+    public init(stringLiteral value: String) {
+        self.init(tolerant: value)!
+    }
+}
diff --git a/Sources/XcodeGen/main.swift b/Sources/XcodeGen/main.swift
index eb21cff2..b71fdfa8 100644
--- a/Sources/XcodeGen/main.swift
+++ b/Sources/XcodeGen/main.swift
@@ -1,6 +1,7 @@
 import Foundation
 import ProjectSpec
 import XcodeGenCLI
+import Version
 
 let version = Version("2.13.0")
 let cli = XcodeGenCLI(version: version)
diff --git a/Sources/XcodeGenCLI/Commands/DumpCommand.swift b/Sources/XcodeGenCLI/Commands/DumpCommand.swift
index dc30fbda..0f84a160 100644
--- a/Sources/XcodeGenCLI/Commands/DumpCommand.swift
+++ b/Sources/XcodeGenCLI/Commands/DumpCommand.swift
@@ -3,6 +3,7 @@ import SwiftCLI
 import PathKit
 import ProjectSpec
 import Yams
+import Version
 
 class DumpCommand: ProjectCommand {
 
diff --git a/Sources/XcodeGenCLI/Commands/GenerateCommand.swift b/Sources/XcodeGenCLI/Commands/GenerateCommand.swift
index c01c7b9a..bfea587e 100644
--- a/Sources/XcodeGenCLI/Commands/GenerateCommand.swift
+++ b/Sources/XcodeGenCLI/Commands/GenerateCommand.swift
@@ -4,6 +4,7 @@ import ProjectSpec
 import SwiftCLI
 import XcodeGenKit
 import XcodeProj
+import Version
 
 class GenerateCommand: ProjectCommand {
 
diff --git a/Sources/XcodeGenCLI/Commands/ProjectCommand.swift b/Sources/XcodeGenCLI/Commands/ProjectCommand.swift
index 7bb9dac8..1ae7816d 100644
--- a/Sources/XcodeGenCLI/Commands/ProjectCommand.swift
+++ b/Sources/XcodeGenCLI/Commands/ProjectCommand.swift
@@ -4,6 +4,7 @@ import ProjectSpec
 import XcodeGenKit
 import PathKit
 import Core
+import Version
 
 class ProjectCommand: Command {
 
diff --git a/Sources/XcodeGenCLI/XcodeGenCLI.swift b/Sources/XcodeGenCLI/XcodeGenCLI.swift
index 32936561..42afef03 100644
--- a/Sources/XcodeGenCLI/XcodeGenCLI.swift
+++ b/Sources/XcodeGenCLI/XcodeGenCLI.swift
@@ -1,6 +1,7 @@
 import Foundation
 import ProjectSpec
 import SwiftCLI
+import Version
 
 public class XcodeGenCLI {
     let cli: CLI
@@ -10,7 +11,7 @@ public class XcodeGenCLI {
 
         cli = CLI(
             name: "xcodegen",
-            version: version.string,
+            version: version.description,
             description: "Generates Xcode projects",
             commands: [
                 generateCommand,
diff --git a/Sources/XcodeGenKit/PBXProjGenerator.swift b/Sources/XcodeGenKit/PBXProjGenerator.swift
index c8bfcd91..17abd007 100644
--- a/Sources/XcodeGenKit/PBXProjGenerator.swift
+++ b/Sources/XcodeGenKit/PBXProjGenerator.swift
@@ -3,6 +3,7 @@ import PathKit
 import ProjectSpec
 import XcodeProj
 import Yams
+import Version
 
 public class PBXProjGenerator {
 
@@ -427,7 +428,7 @@ public class PBXProjGenerator {
         let buildSettings = defaultConfiguration.buildSettings
         let settings = Settings(buildSettings: buildSettings, configSettings: [:], groups: [])
         let deploymentTargetString = buildSettings[platform.deploymentTargetSetting] as? String
-        let deploymentTarget = deploymentTargetString == nil ? nil : try Version(deploymentTargetString!)
+        let deploymentTarget = deploymentTargetString == nil ? nil : try Version.parse(deploymentTargetString!)
         let requiresObjCLinking = (buildSettings["OTHER_LDFLAGS"] as? String)?.contains("-ObjC") ?? (productType == .staticLibrary)
         let dependencyTarget = Target(
             name: targetObject.name,
@@ -778,7 +779,7 @@ public class PBXProjGenerator {
                     ? carthageResolver.relatedDependencies(for: dependency, in: target.platform) : [dependency]
                 allDependencies.forEach { dependency in
 
-                    var platformPath = Path(carthageResolver.buildPath(for: target.platform, linkType: linkType))
+                    let platformPath = Path(carthageResolver.buildPath(for: target.platform, linkType: linkType))
                     var frameworkPath = platformPath + dependency.reference
                     if frameworkPath.extension == nil {
                         frameworkPath = Path(frameworkPath.string + ".framework")
diff --git a/Tests/ProjectSpecTests/ProjectSpecTests.swift b/Tests/ProjectSpecTests/ProjectSpecTests.swift
index 39b4f50a..1e163163 100644
--- a/Tests/ProjectSpecTests/ProjectSpecTests.swift
+++ b/Tests/ProjectSpecTests/ProjectSpecTests.swift
@@ -4,6 +4,7 @@ import Spectre
 import XcodeProj
 import XCTest
 import TestSupport
+import Version
 
 class ProjectSpecTests: XCTestCase {
 
@@ -50,18 +51,18 @@ class ProjectSpecTests: XCTestCase {
             }
 
             $0.it("parses version correctly") {
-                try expect(Version("2").deploymentTarget) == "2.0"
-                try expect(Version("2.0").deploymentTarget) == "2.0"
-                try expect(Version("2.1").deploymentTarget) == "2.1"
-                try expect(Version("2.10").deploymentTarget) == "2.10"
-                try expect(Version("2.1.0").deploymentTarget) == "2.1"
-                try expect(Version("2.12.0").deploymentTarget) == "2.12"
-                try expect(Version("2.1.2").deploymentTarget) == "2.1.2"
-                try expect(Version("2.10.2").deploymentTarget) == "2.10.2"
-                try expect(Version("2.0.2").deploymentTarget) == "2.0.2"
-                try expect(Version(2).deploymentTarget) == "2.0"
-                try expect(Version(2.0).deploymentTarget) == "2.0"
-                try expect(Version(2.1).deploymentTarget) == "2.1"
+                try expect(Version.parse("2").deploymentTarget) == "2.0"
+                try expect(Version.parse("2.0").deploymentTarget) == "2.0"
+                try expect(Version.parse("2.1").deploymentTarget) == "2.1"
+                try expect(Version.parse("2.10").deploymentTarget) == "2.10"
+                try expect(Version.parse("2.1.0").deploymentTarget) == "2.1"
+                try expect(Version.parse("2.12.0").deploymentTarget) == "2.12"
+                try expect(Version.parse("2.1.2").deploymentTarget) == "2.1.2"
+                try expect(Version.parse("2.10.2").deploymentTarget) == "2.10.2"
+                try expect(Version.parse("2.0.2").deploymentTarget) == "2.0.2"
+                try expect(Version.parse(2).deploymentTarget) == "2.0"
+                try expect(Version.parse(2.0).deploymentTarget) == "2.0"
+                try expect(Version.parse(2.1).deploymentTarget) == "2.1"
             }
         }
     }
@@ -76,7 +77,7 @@ class ProjectSpecTests: XCTestCase {
             )
 
             $0.it("fails with invalid XcodeGen version") {
-                let minimumVersion = Version("1.11.1")
+                let minimumVersion = try Version.parse("1.11.1")
                 var project = baseProject
                 project.options = SpecOptions(minimumXcodeGenVersion: minimumVersion)
 
@@ -86,9 +87,9 @@ class ProjectSpecTests: XCTestCase {
                     }
                 }
 
-                try expectMinimumXcodeGenVersionError(project, minimumVersion: minimumVersion, xcodeGenVersion: Version("1.11.0"))
-                try expectMinimumXcodeGenVersionError(project, minimumVersion: minimumVersion, xcodeGenVersion: Version("1.10.99"))
-                try expectMinimumXcodeGenVersionError(project, minimumVersion: minimumVersion, xcodeGenVersion: Version("0.99"))
+                try expectMinimumXcodeGenVersionError(project, minimumVersion: minimumVersion, xcodeGenVersion: Version.parse("1.11.0"))
+                try expectMinimumXcodeGenVersionError(project, minimumVersion: minimumVersion, xcodeGenVersion: Version.parse("1.10.99"))
+                try expectMinimumXcodeGenVersionError(project, minimumVersion: minimumVersion, xcodeGenVersion: Version.parse("0.99"))
             }
 
             $0.it("fails with invalid project") {
diff --git a/Tests/ProjectSpecTests/SpecLoadingTests.swift b/Tests/ProjectSpecTests/SpecLoadingTests.swift
index beab9d2b..c1d3a765 100644
--- a/Tests/ProjectSpecTests/SpecLoadingTests.swift
+++ b/Tests/ProjectSpecTests/SpecLoadingTests.swift
@@ -6,6 +6,7 @@ import XcodeProj
 import XCTest
 import Yams
 import TestSupport
+import Version
 
 class SpecLoadingTests: XCTestCase {
 
@@ -1101,6 +1102,7 @@ class SpecLoadingTests: XCTestCase {
                     "package5": SwiftPackage(url: "package.git", versionRequirement: .revision("x")),
                     "package6": SwiftPackage(url: "package.git", versionRequirement: .range(from: "1.2.0", to: "1.2.5")),
                     "package7": SwiftPackage(url: "package.git", versionRequirement: .exact("1.2.2")),
+                    "package8": SwiftPackage(url: "package.git", versionRequirement: .upToNextMajorVersion("4.0.0-beta.5")),
                 ],
                                       localPackages: ["../../Package"],
                                       options: .init(localPackagesGroup: "MyPackages"))
@@ -1118,6 +1120,7 @@ class SpecLoadingTests: XCTestCase {
                         "package5": ["url": "package.git", "revision": "x"],
                         "package6": ["url": "package.git", "minVersion": "1.2.0", "maxVersion": "1.2.5"],
                         "package7": ["url": "package.git", "version": "1.2.2"],
+                        "package8": ["url": "package.git", "majorVersion": "4.0.0-beta.5"],
                     ],
                     "localPackages": ["../../Package"],
                 ]