diff --git a/Examples/BackgroundTasks/Sources/main.swift b/Examples/BackgroundTasks/Sources/main.swift
index 929e676a..1985fc34 100644
--- a/Examples/BackgroundTasks/Sources/main.swift
+++ b/Examples/BackgroundTasks/Sources/main.swift
@@ -13,7 +13,12 @@
 //===----------------------------------------------------------------------===//
 
 import AWSLambdaRuntime
+
+#if canImport(FoundationEssentials)
+import FoundationEssentials
+#else
 import Foundation
+#endif
 
 struct BackgroundProcessingHandler: LambdaWithBackgroundProcessingHandler {
     struct Input: Decodable {
diff --git a/Sources/AWSLambdaRuntime/Context+Foundation.swift b/Sources/AWSLambdaRuntime/Context+Foundation.swift
index a83237a7..105b7765 100644
--- a/Sources/AWSLambdaRuntime/Context+Foundation.swift
+++ b/Sources/AWSLambdaRuntime/Context+Foundation.swift
@@ -14,7 +14,11 @@
 
 import AWSLambdaRuntimeCore
 
+#if canImport(FoundationEssentials)
+import FoundationEssentials
+#else
 import struct Foundation.Date
+#endif
 
 extension LambdaContext {
     var deadlineDate: Date {
diff --git a/Sources/AWSLambdaRuntime/Vendored/ByteBuffer-foundation.swift b/Sources/AWSLambdaRuntime/Vendored/ByteBuffer-foundation.swift
index e0b6cf5e..8dbd7326 100644
--- a/Sources/AWSLambdaRuntime/Vendored/ByteBuffer-foundation.swift
+++ b/Sources/AWSLambdaRuntime/Vendored/ByteBuffer-foundation.swift
@@ -26,9 +26,14 @@
 //
 //===----------------------------------------------------------------------===//
 
-import Foundation
 import NIOCore
 
+#if canImport(FoundationEssentials)
+import FoundationEssentials
+#else
+import Foundation
+#endif
+
 // This is NIO's `NIOFoundationCompat` module which at the moment only adds `ByteBuffer` utility methods
 // for Foundation's `Data` type.
 //
diff --git a/Sources/AWSLambdaRuntimeCore/LambdaRuntime.swift b/Sources/AWSLambdaRuntimeCore/LambdaRuntime.swift
index f10f07b1..317ee7ea 100644
--- a/Sources/AWSLambdaRuntimeCore/LambdaRuntime.swift
+++ b/Sources/AWSLambdaRuntimeCore/LambdaRuntime.swift
@@ -12,11 +12,16 @@
 //
 //===----------------------------------------------------------------------===//
 
-import Foundation
 import Logging
 import NIOConcurrencyHelpers
 import NIOCore
 
+#if canImport(FoundationEssentials)
+import FoundationEssentials
+#else
+import Foundation
+#endif
+
 // We need `@unchecked` Sendable here, as `NIOLockedValueBox` does not understand `sending` today.
 // We don't want to use `NIOLockedValueBox` here anyway. We would love to use Mutex here, but this
 // sadly crashes the compiler today.
diff --git a/Sources/MockServer/main.swift b/Sources/MockServer/main.swift
index 9bed33bd..1b8466f9 100644
--- a/Sources/MockServer/main.swift
+++ b/Sources/MockServer/main.swift
@@ -12,11 +12,17 @@
 //
 //===----------------------------------------------------------------------===//
 
-import Foundation
+import Dispatch
 import NIOCore
 import NIOHTTP1
 import NIOPosix
 
+#if canImport(FoundationEssentials)
+import FoundationEssentials
+#else
+import Foundation
+#endif
+
 struct MockServer {
     private let group: EventLoopGroup
     private let host: String
diff --git a/Tests/AWSLambdaRuntimeCoreTests/InvocationTests.swift b/Tests/AWSLambdaRuntimeCoreTests/InvocationTests.swift
index 86bfaae9..fca58391 100644
--- a/Tests/AWSLambdaRuntimeCoreTests/InvocationTests.swift
+++ b/Tests/AWSLambdaRuntimeCoreTests/InvocationTests.swift
@@ -12,12 +12,17 @@
 //
 //===----------------------------------------------------------------------===//
 
-import Foundation
 import NIOHTTP1
 import Testing
 
 @testable import AWSLambdaRuntimeCore
 
+#if canImport(FoundationEssentials)
+import FoundationEssentials
+#else
+import Foundation
+#endif
+
 @Suite
 struct InvocationTest {
     @Test
diff --git a/Tests/AWSLambdaRuntimeCoreTests/LambdaMockClient.swift b/Tests/AWSLambdaRuntimeCoreTests/LambdaMockClient.swift
index 15a30223..613276ed 100644
--- a/Tests/AWSLambdaRuntimeCoreTests/LambdaMockClient.swift
+++ b/Tests/AWSLambdaRuntimeCoreTests/LambdaMockClient.swift
@@ -13,10 +13,15 @@
 //===----------------------------------------------------------------------===//
 
 import AWSLambdaRuntimeCore
-import Foundation
 import Logging
 import NIOCore
 
+#if canImport(FoundationEssentials)
+import FoundationEssentials
+#else
+import Foundation
+#endif
+
 struct LambdaMockWriter: LambdaRuntimeClientResponseStreamWriter {
     var underlying: LambdaMockClient
 
diff --git a/Tests/AWSLambdaRuntimeCoreTests/LambdaRequestIDTests.swift b/Tests/AWSLambdaRuntimeCoreTests/LambdaRequestIDTests.swift
index 9e406fdf..45886c64 100644
--- a/Tests/AWSLambdaRuntimeCoreTests/LambdaRequestIDTests.swift
+++ b/Tests/AWSLambdaRuntimeCoreTests/LambdaRequestIDTests.swift
@@ -12,12 +12,17 @@
 //
 //===----------------------------------------------------------------------===//
 
-import Foundation
 import NIOCore
 import Testing
 
 @testable import AWSLambdaRuntimeCore
 
+#if canImport(FoundationEssentials)
+import FoundationEssentials
+#else
+import Foundation
+#endif
+
 @Suite("LambdaRequestID tests")
 struct LambdaRequestIDTest {
     @Test
@@ -100,6 +105,7 @@ struct LambdaRequestIDTest {
         #expect(buffer.readableBytes == readableBeforeRead)
     }
 
+    #if os(macOS)
     @Test
     func testInitFromNSStringSuccess() {
         let nsString = NSMutableString(capacity: 16)
@@ -121,6 +127,7 @@ struct LambdaRequestIDTest {
         #expect(requestID?.uuidString == LambdaRequestID(uuidString: nsString as String)?.uuidString)
         #expect(requestID?.uppercased == nsString as String)
     }
+    #endif
 
     @Test
     func testUnparse() {
diff --git a/Tests/AWSLambdaRuntimeCoreTests/LambdaRunLoopTests.swift b/Tests/AWSLambdaRuntimeCoreTests/LambdaRunLoopTests.swift
index 741bbf50..f57f051b 100644
--- a/Tests/AWSLambdaRuntimeCoreTests/LambdaRunLoopTests.swift
+++ b/Tests/AWSLambdaRuntimeCoreTests/LambdaRunLoopTests.swift
@@ -12,13 +12,18 @@
 //
 //===----------------------------------------------------------------------===//
 
-import Foundation
 import Logging
 import NIOCore
 import Testing
 
 @testable import AWSLambdaRuntimeCore
 
+#if canImport(FoundationEssentials)
+import FoundationEssentials
+#else
+import Foundation
+#endif
+
 @Suite
 struct LambdaRunLoopTests {
     struct MockEchoHandler: StreamingLambdaHandler {
diff --git a/Tests/AWSLambdaRuntimeCoreTests/MockLambdaServer.swift b/Tests/AWSLambdaRuntimeCoreTests/MockLambdaServer.swift
index cc3c4ac2..dc325742 100644
--- a/Tests/AWSLambdaRuntimeCoreTests/MockLambdaServer.swift
+++ b/Tests/AWSLambdaRuntimeCoreTests/MockLambdaServer.swift
@@ -12,7 +12,6 @@
 //
 //===----------------------------------------------------------------------===//
 
-import Foundation  // for JSON
 import Logging
 import NIOCore
 import NIOHTTP1
@@ -20,6 +19,12 @@ import NIOPosix
 
 @testable import AWSLambdaRuntimeCore
 
+#if canImport(FoundationEssentials)
+import FoundationEssentials
+#else
+import Foundation
+#endif
+
 func withMockServer<Result>(
     behaviour: some LambdaServerBehavior,
     port: Int = 0,
diff --git a/Tests/AWSLambdaRuntimeCoreTests/Utils.swift b/Tests/AWSLambdaRuntimeCoreTests/Utils.swift
index cd7730b7..49a3cfbb 100644
--- a/Tests/AWSLambdaRuntimeCoreTests/Utils.swift
+++ b/Tests/AWSLambdaRuntimeCoreTests/Utils.swift
@@ -12,7 +12,11 @@
 //
 //===----------------------------------------------------------------------===//
 
+#if canImport(FoundationEssentials)
+import FoundationEssentials
+#else
 import Foundation
+#endif
 
 extension Date {
     var millisSinceEpoch: Int64 {
diff --git a/readme.md b/readme.md
index 7c42587e..0717c3e3 100644
--- a/readme.md
+++ b/readme.md
@@ -253,7 +253,11 @@ Background tasks allow code to execute asynchronously after the main response ha
 Here is an example of a minimal function that waits 10 seconds after it returned a response but before the handler returns.
 ```swift
 import AWSLambdaRuntime
+#if canImport(FoundationEssentials)
+import FoundationEssentials
+#else
 import Foundation
+#endif
 
 struct BackgroundProcessingHandler: LambdaWithBackgroundProcessingHandler {
     struct Input: Decodable {