diff --git a/.circleci/config.yml b/.circleci/config.yml
index 8ddf818..3a577cb 100644
--- a/.circleci/config.yml
+++ b/.circleci/config.yml
@@ -1,9 +1,22 @@
 version: 2
 jobs:
-  build:
+  macOS_swift_4.1:
     macos:
-      xcode: "9.2.0"
+      xcode: "9.3.0"
     steps:
       - checkout
       - run: swift build
       - run: swift test
+  linux_swift_4.1:
+    docker:
+      - image: norionomura/swift:41
+    steps:
+      - checkout
+      - run: swift build
+      - run: swift test
+workflows:
+  version: 2
+  workflow:
+    jobs:
+      - macOS_swift_4.1
+      - linux_swift_4.1
\ No newline at end of file
diff --git a/README.md b/README.md
index 4f0a2fb..5b8af97 100644
--- a/README.md
+++ b/README.md
@@ -1,6 +1,7 @@
 # Beak 🐦
 
 [![SPM](https://img.shields.io/badge/Swift_PM-compatible-brightgreen.svg?style=for-the-badge)](https://swift.org/package-manager)
+![Linux](https://img.shields.io/badge/Platforms-macOS_Linux-blue.svg?style=for-the-badge)
 [![Git Version](https://img.shields.io/github/release/yonaskolb/Beak.svg?style=for-the-badge)](https://github.com/yonaskolb/Beak/releases)
 [![Build Status](https://img.shields.io/circleci/project/github/yonaskolb/Beak.svg?style=for-the-badge)](https://circleci.com/gh/yonaskolb/Beak)
 [![license](https://img.shields.io/github/license/yonaskolb/Beak.svg?style=for-the-badge)](https://github.com/yonaskolb/Beak/blob/master/LICENSE)
diff --git a/Sources/BeakCore/SourceKit.swift b/Sources/BeakCore/SourceKit.swift
index 8a7ff68..667c5ef 100644
--- a/Sources/BeakCore/SourceKit.swift
+++ b/Sources/BeakCore/SourceKit.swift
@@ -83,7 +83,7 @@ enum Substring {
     }
 
     func extract(from source: [String: SourceKitRepresentable], contents: String) -> String? {
-        let substring = range(for: source).flatMap { contents.substringWithByteRange(start: Int($0.offset), length: Int($0.length)) }
+        let substring = range(for: source).flatMap { contents.substring(start: Int($0.offset), length: Int($0.length)) }
         return substring?.isEmpty == true ? nil : substring?.trimmingCharacters(in: .whitespacesAndNewlines)
     }
 }
diff --git a/Tests/BeakTests/XCTestManifests.swift b/Tests/BeakTests/XCTestManifests.swift
new file mode 100644
index 0000000..cbd8500
--- /dev/null
+++ b/Tests/BeakTests/XCTestManifests.swift
@@ -0,0 +1,15 @@
+import XCTest
+
+extension BeakTests {
+    static let __allTests = [
+        ("testBeak", testBeak),
+    ]
+}
+
+#if !os(macOS)
+public func __allTests() -> [XCTestCaseEntry] {
+    return [
+        testCase(BeakTests.__allTests),
+    ]
+}
+#endif
diff --git a/Tests/LinuxMain.swift b/Tests/LinuxMain.swift
new file mode 100644
index 0000000..d158229
--- /dev/null
+++ b/Tests/LinuxMain.swift
@@ -0,0 +1,8 @@
+import XCTest
+
+import BeakTests
+
+var tests = [XCTestCaseEntry]()
+tests += BeakTests.__allTests()
+
+XCTMain(tests)