diff --git a/Sources/AmiiboService/Public/Protocols/AmiiboClient.swift b/Sources/AmiiboService/Public/Protocols/AmiiboClient.swift
index ff9f80a..6cd3c5f 100644
--- a/Sources/AmiiboService/Public/Protocols/AmiiboClient.swift
+++ b/Sources/AmiiboService/Public/Protocols/AmiiboClient.swift
@@ -15,7 +15,9 @@
 import Foundation
 
 /// A protocol that defines API clients containing all available endpoints to interact with.
-public protocol AmiiboClient {
+///
+/// Conforming types must be `Sendable`, as clients are expected to be used safely across concurrency domains.
+public protocol AmiiboClient: Sendable {
     
     // MARK: Functions
     
diff --git a/Sources/AmiiboService/Public/Services/AmiiboService.swift b/Sources/AmiiboService/Public/Services/AmiiboService.swift
index 9cdac1b..608d045 100644
--- a/Sources/AmiiboService/Public/Services/AmiiboService.swift
+++ b/Sources/AmiiboService/Public/Services/AmiiboService.swift
@@ -15,7 +15,7 @@
 import Foundation
 
 /// A type that implements the service that uses a client to make calls.
-public struct AmiiboService {
+public struct AmiiboService: Sendable {
     
     // MARK: Properties