diff --git a/Package.swift b/Package.swift
index 5cd1b0f..8bf4bba 100644
--- a/Package.swift
+++ b/Package.swift
@@ -1,4 +1,4 @@
-// swift-tools-version:5.7
+// swift-tools-version:5.8
 import PackageDescription
 
 let package = Package(
@@ -19,12 +19,26 @@ let package = Package(
             name: "Instrumentation",
             dependencies: [
                 .product(name: "ServiceContextModule", package: "swift-service-context"),
+            ],
+            swiftSettings: [
+              .enableExperimentalFeature("StrictConcurrency"),
+              .unsafeFlags([
+                "-Xfrontend", "-disable-availability-checking"
+//                "-enable-experimental-feature IsolatedAny"
+              ])
             ]
         ),
         .testTarget(
             name: "InstrumentationTests",
             dependencies: [
                 .target(name: "Instrumentation"),
+            ],
+            swiftSettings: [
+              .enableExperimentalFeature("StrictConcurrency"),
+              .unsafeFlags([
+                "-Xfrontend", "-disable-availability-checking"
+//                "-enable-experimental-feature IsolatedAny"
+              ])
             ]
         ),
 
@@ -35,12 +49,26 @@ let package = Package(
             name: "Tracing",
             dependencies: [
                 .target(name: "Instrumentation"),
+            ],
+            swiftSettings: [
+              .enableExperimentalFeature("StrictConcurrency"),
+              .unsafeFlags([
+                "-Xfrontend", "-disable-availability-checking"
+//                "-enable-experimental-feature IsolatedAny"
+              ])
             ]
         ),
         .testTarget(
             name: "TracingTests",
             dependencies: [
                 .target(name: "Tracing"),
+            ],
+            swiftSettings: [
+              .enableExperimentalFeature("StrictConcurrency"),
+              .unsafeFlags([
+                "-Xfrontend", "-disable-availability-checking"
+//                "-enable-experimental-feature IsolatedAny"
+              ])
             ]
         ),
     ]
diff --git a/Sources/Tracing/Tracer.swift b/Sources/Tracing/Tracer.swift
index 726aa88..623ebc6 100644
--- a/Sources/Tracing/Tracer.swift
+++ b/Sources/Tracing/Tracer.swift
@@ -330,6 +330,7 @@ public func withSpan<T, Instant: TracerInstant>(
     function: String = #function,
     file fileID: String = #fileID,
     line: UInt = #line,
+    isolation: isolated (any Actor)? = #isolation,
     _ operation: (any Span) async throws -> T
 ) async rethrows -> T {
     try await InstrumentationSystem.legacyTracer.withAnySpan(
@@ -375,6 +376,7 @@ public func withSpan<T>(
     function: String = #function,
     file fileID: String = #fileID,
     line: UInt = #line,
+    isolation: isolated (any Actor)? = #isolation,
     _ operation: (any Span) async throws -> T
 ) async rethrows -> T {
     try await InstrumentationSystem.legacyTracer.withAnySpan(
@@ -384,7 +386,8 @@ public func withSpan<T>(
         ofKind: kind,
         function: function,
         file: fileID,
-        line: line
+        line: line,
+        isolation: isolation
     ) { anySpan in
         try await operation(anySpan)
     }
@@ -422,6 +425,7 @@ public func withSpan<T>(
     function: String = #function,
     file fileID: String = #fileID,
     line: UInt = #line,
+    isolation: isolated (any Actor)? = #isolation,
     _ operation: (any Span) async throws -> T
 ) async rethrows -> T {
     try await InstrumentationSystem.legacyTracer.withAnySpan(
@@ -431,7 +435,8 @@ public func withSpan<T>(
         ofKind: kind,
         function: function,
         file: fileID,
-        line: line
+        line: line,
+        isolation: isolation
     ) { anySpan in
         try await operation(anySpan)
     }
diff --git a/Sources/Tracing/TracerProtocol+Legacy.swift b/Sources/Tracing/TracerProtocol+Legacy.swift
index 3426cc9..2a26942 100644
--- a/Sources/Tracing/TracerProtocol+Legacy.swift
+++ b/Sources/Tracing/TracerProtocol+Legacy.swift
@@ -306,6 +306,7 @@ extension LegacyTracer {
     ///   - operation: The operation that this span should be measuring
     /// - Returns: the value returned by `operation`
     /// - Throws: the error the `operation` has thrown (if any)
+    @available(macOS 10.15, iOS 13, tvOS 13, watchOS 6, *) // for #isolation
     public func withAnySpan<T, Instant: TracerInstant>(
         _ operationName: String,
         at instant: @autoclosure () -> Instant,
@@ -314,6 +315,7 @@ extension LegacyTracer {
         function: String = #function,
         file fileID: String = #fileID,
         line: UInt = #line,
+        isolation: isolated (any Actor)? = #isolation,
         _ operation: (any Tracing.Span) async throws -> T
     ) async rethrows -> T {
         let span = self.startAnySpan(
@@ -360,6 +362,7 @@ extension LegacyTracer {
     ///   - operation: The operation that this span should be measuring
     /// - Returns: the value returned by `operation`
     /// - Throws: the error the `operation` has thrown (if any)
+    @available(macOS 10.15, iOS 13, tvOS 13, watchOS 6, *) // for #isolation
     public func withAnySpan<T>(
         _ operationName: String,
         context: @autoclosure () -> ServiceContext = .current ?? .topLevel,
@@ -367,6 +370,7 @@ extension LegacyTracer {
         function: String = #function,
         file fileID: String = #fileID,
         line: UInt = #line,
+        isolation: isolated (any Actor)? = #isolation,
         _ operation: (any Tracing.Span) async throws -> T
     ) async rethrows -> T {
         let span = self.startAnySpan(
@@ -530,6 +534,7 @@ extension Tracer {
     ///   - operation: The operation that this span should be measuring
     /// - Returns: the value returned by `operation`
     /// - Throws: the error the `operation` has thrown (if any)
+    @available(macOS 10.15, iOS 13, tvOS 13, watchOS 6, *) // for #isolation
     public func withAnySpan<T>(
         _ operationName: String,
         at instant: @autoclosure () -> some TracerInstant = DefaultTracerClock.now,
@@ -538,7 +543,8 @@ extension Tracer {
         function: String = #function,
         file fileID: String = #fileID,
         line: UInt = #line,
-        @_inheritActorContext @_implicitSelfCapture _ operation: (any Tracing.Span) async throws -> T
+        isolation: isolated (any Actor)? = #isolation,
+        _ operation: (any Tracing.Span) async throws -> T
     ) async rethrows -> T {
         try await self.withSpan(
             operationName,
@@ -547,7 +553,8 @@ extension Tracer {
             at: instant(),
             function: function,
             file: fileID,
-            line: line
+            line: line,
+            isolation: isolation
         ) { span in
             try await operation(span)
         }
diff --git a/Sources/Tracing/TracerProtocol.swift b/Sources/Tracing/TracerProtocol.swift
index 0a0a13d..de08489 100644
--- a/Sources/Tracing/TracerProtocol.swift
+++ b/Sources/Tracing/TracerProtocol.swift
@@ -248,7 +248,8 @@ extension Tracer {
         function: String = #function,
         file fileID: String = #fileID,
         line: UInt = #line,
-        @_inheritActorContext @_implicitSelfCapture _ operation: (Self.Span) async throws -> T
+        isolation: isolated (any Actor)? = #isolation,
+        _ operation: (Self.Span) async throws -> T
     ) async rethrows -> T {
         let span = self.startSpan(
             operationName,
@@ -301,7 +302,8 @@ extension Tracer {
         function: String = #function,
         file fileID: String = #fileID,
         line: UInt = #line,
-        @_inheritActorContext @_implicitSelfCapture _ operation: (Self.Span) async throws -> T
+        isolation: isolated (any Actor)? = #isolation,
+        _ operation: (Self.Span) async throws -> T
     ) async rethrows -> T {
         let span = self.startSpan(
             operationName,