diff --git a/.devcontainer/devcontainer.json b/.devcontainer/devcontainer.json
index f831472..991b68a 100644
--- a/.devcontainer/devcontainer.json
+++ b/.devcontainer/devcontainer.json
@@ -1,12 +1,12 @@
 {
     "name": "Swift",
-    "image": "swift:5.9.1",
+    "image": "swift:6.0",
     "features": {
         "ghcr.io/devcontainers/features/common-utils:2": {
             "installZsh": "false",
             "username": "vscode",
-            "userUid": "1000",
-            "userGid": "1000",
+            "userUid": "1001",
+            "userGid": "1001",
             "upgradePackages": "false"
         },
         "ghcr.io/devcontainers/features/git:1": {
diff --git a/.github/workflows/swift.yml b/.github/workflows/swift-5.9.yml
similarity index 68%
rename from .github/workflows/swift.yml
rename to .github/workflows/swift-5.9.yml
index b021b75..66f9bb8 100644
--- a/.github/workflows/swift.yml
+++ b/.github/workflows/swift-5.9.yml
@@ -1,4 +1,4 @@
-name: Unit Test
+name: Test Swift 5.9
 
 on:
   push:
@@ -8,11 +8,11 @@ on:
 
 jobs:
   build:
-
+    container: swift:5.9
     runs-on: ubuntu-latest
     steps:
     - uses: actions/checkout@v4
     - name: Build
-      run: swift build -v
+      run: swift build
     - name: Run tests
-      run: swift test -v
+      run: swift test
diff --git a/.github/workflows/swift-6.0.yml b/.github/workflows/swift-6.0.yml
new file mode 100644
index 0000000..a6b7b99
--- /dev/null
+++ b/.github/workflows/swift-6.0.yml
@@ -0,0 +1,18 @@
+name: Test Swift 6.0
+
+on:
+  push:
+    branches: [ main ]
+  pull_request:
+    branches: [ main ]
+
+jobs:
+  build:
+    container: swift:6.0
+    runs-on: ubuntu-latest
+    steps:
+    - uses: actions/checkout@v4
+    - name: Build
+      run: swift build
+    - name: Run tests
+      run: swift test
diff --git a/Package.swift b/Package.swift
index c70ff14..f2ceb2c 100644
--- a/Package.swift
+++ b/Package.swift
@@ -25,7 +25,8 @@ let package = Package(
         .testTarget(
             name: "DataDogLogTests",
             dependencies: ["DataDogLog"]),
-    ]
+    ],
+    swiftLanguageVersions: [.version("6"), .v5]
 )
 
 #if os(Linux)
diff --git a/Sources/DataDogLog/Internal/Extensions/String+Timestamp.swift b/Sources/DataDogLog/Internal/Extensions/String+Timestamp.swift
index c020a1a..dd1696a 100644
--- a/Sources/DataDogLog/Internal/Extensions/String+Timestamp.swift
+++ b/Sources/DataDogLog/Internal/Extensions/String+Timestamp.swift
@@ -4,8 +4,11 @@ extension String {
     static var timestamp: String {
         var buffer = [Int8](repeating: 0, count: 255)
         var timestamp = time(nil)
-        let localTime = localtime(&timestamp)
+        guard let localTime = localtime(&timestamp) else {
+            return "<unknown>"
+        }
         strftime(&buffer, buffer.count, "%Y-%m-%dT%H:%M:%S%z", localTime)
+
         return buffer.withUnsafeBufferPointer {
             $0.withMemoryRebound(to: CChar.self) {
                 String(cString: $0.baseAddress!)
diff --git a/Sources/DataDogLog/Internal/NetworkClient.swift b/Sources/DataDogLog/Internal/NetworkClient.swift
index d2cfe65..b39daa1 100644
--- a/Sources/DataDogLog/Internal/NetworkClient.swift
+++ b/Sources/DataDogLog/Internal/NetworkClient.swift
@@ -24,7 +24,7 @@ final class NetworkClient: Sendable {
 
     deinit {
 #if os(Linux)
-        client.shutdown()
+        client.shutdown { _ in }
 #endif
     }