diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index f5c509e..236277b 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -19,6 +19,7 @@ jobs:
     strategy:
       matrix:
         xcode:
+          - "26.2"
           - "26.5"
     steps:
       - uses: actions/checkout@v5
@@ -26,6 +27,13 @@ jobs:
         run: sudo xcode-select -s /Applications/Xcode_${{ matrix.xcode }}.app
       - name: Print Swift version
         run: swift --version
+      - name: Install Simulator Runtimes
+        if: matrix.xcode != '26.2'
+        uses: nick-fields/retry@v3
+        with:
+          timeout_minutes: 15
+          max_attempts: 3
+          command: xcodebuild -downloadAllPlatforms
       - name: Run ${{ matrix.config }} tests
         run: CONFIG=${{ matrix.config }} make test-all
 
@@ -36,6 +44,7 @@ jobs:
       matrix:
         config: ["debug", "release"]
         swift:
+          - "6.0"
           - "6.3"
     container: swift:${{ matrix.swift }}
     steps:
diff --git a/Sources/Clocks/ImmediateClock.swift b/Sources/Clocks/ImmediateClock.swift
index f182e7f..ac33425 100644
--- a/Sources/Clocks/ImmediateClock.swift
+++ b/Sources/Clocks/ImmediateClock.swift
@@ -133,18 +133,17 @@
       }
     }
 
-    public private(set) var now: Instant
+    public internal(set) var now: Instant
     public private(set) var minimumResolution: Duration = .zero
-    private let lock = NSLock()
+    let lock = NSLock()
 
     public init(now: Instant = .init()) {
       self.now = now
     }
 
-    public func sleep(until deadline: Instant, tolerance: Duration?) async throws {
+    public func sleep(until deadline: Instant, tolerance: Duration?) throws {
       try Task.checkCancellation()
       self.lock.sync { self.now = deadline }
-      await Task.megaYield()
     }
   }
 
diff --git a/Sources/Clocks/NonsendingClock.swift b/Sources/Clocks/NonsendingClock.swift
new file mode 100644
index 0000000..497f230
--- /dev/null
+++ b/Sources/Clocks/NonsendingClock.swift
@@ -0,0 +1,34 @@
+#if compiler(>=6.2)
+  @available(iOS 16, macOS 13, tvOS 16, watchOS 9, *)
+  public protocol NonsendingClock<Duration>: Clock {
+    nonisolated(nonsending)
+      func sleep(until deadline: Instant, tolerance: Instant.Duration?) async throws
+  }
+
+  @available(iOS 16, macOS 13, tvOS 16, watchOS 9, *)
+  extension NonsendingClock {
+    nonisolated(nonsending)
+      public func sleep(for duration: Duration, tolerance: Instant.Duration? = nil) async throws
+    {
+      try await sleep(until: now.advanced(by: duration), tolerance: tolerance)
+    }
+  }
+
+  @available(iOS 16, macOS 13, tvOS 16, watchOS 9, *)
+  extension AnyClock: NonsendingClock {}
+
+  @available(iOS 16, macOS 13, tvOS 16, watchOS 9, *)
+  extension ContinuousClock: NonsendingClock {}
+
+  @available(iOS 16, macOS 13, tvOS 16, watchOS 9, *)
+  extension ImmediateClock: NonsendingClock {}
+
+  @available(iOS 16, macOS 13, tvOS 16, watchOS 9, *)
+  extension SuspendingClock: NonsendingClock {}
+
+  @available(iOS 16, macOS 13, tvOS 16, watchOS 9, *)
+  extension TestClock: NonsendingClock {}
+
+  @available(iOS 16, macOS 13, tvOS 16, watchOS 9, *)
+  extension UnimplementedClock: NonsendingClock {}
+#endif