diff --git a/Sources/Examples/Echo/Model/echo.grpc.swift b/Sources/Examples/Echo/Model/echo.grpc.swift
index 599de4587..900fbd2d5 100644
--- a/Sources/Examples/Echo/Model/echo.grpc.swift
+++ b/Sources/Examples/Echo/Model/echo.grpc.swift
@@ -316,7 +316,7 @@ extension Echo_EchoAsyncClientProtocol {
   public func collect<RequestStream>(
     _ requests: RequestStream,
     callOptions: CallOptions? = nil
-  ) async throws -> Echo_EchoResponse where RequestStream: AsyncSequence, RequestStream.Element == Echo_EchoRequest {
+  ) async throws -> Echo_EchoResponse where RequestStream: AsyncSequence & Sendable, RequestStream.Element == Echo_EchoRequest {
     return try await self.performAsyncClientStreamingCall(
       path: Echo_EchoClientMetadata.Methods.collect.path,
       requests: requests,
@@ -340,7 +340,7 @@ extension Echo_EchoAsyncClientProtocol {
   public func update<RequestStream>(
     _ requests: RequestStream,
     callOptions: CallOptions? = nil
-  ) -> GRPCAsyncResponseStream<Echo_EchoResponse> where RequestStream: AsyncSequence, RequestStream.Element == Echo_EchoRequest {
+  ) -> GRPCAsyncResponseStream<Echo_EchoResponse> where RequestStream: AsyncSequence & Sendable, RequestStream.Element == Echo_EchoRequest {
     return self.performAsyncBidirectionalStreamingCall(
       path: Echo_EchoClientMetadata.Methods.update.path,
       requests: requests,
diff --git a/Sources/Examples/RouteGuide/Model/route_guide.grpc.swift b/Sources/Examples/RouteGuide/Model/route_guide.grpc.swift
index c3b0e77a5..641d470cf 100644
--- a/Sources/Examples/RouteGuide/Model/route_guide.grpc.swift
+++ b/Sources/Examples/RouteGuide/Model/route_guide.grpc.swift
@@ -335,7 +335,7 @@ extension Routeguide_RouteGuideAsyncClientProtocol {
   public func recordRoute<RequestStream>(
     _ requests: RequestStream,
     callOptions: CallOptions? = nil
-  ) async throws -> Routeguide_RouteSummary where RequestStream: AsyncSequence, RequestStream.Element == Routeguide_Point {
+  ) async throws -> Routeguide_RouteSummary where RequestStream: AsyncSequence & Sendable, RequestStream.Element == Routeguide_Point {
     return try await self.performAsyncClientStreamingCall(
       path: Routeguide_RouteGuideClientMetadata.Methods.recordRoute.path,
       requests: requests,
@@ -359,7 +359,7 @@ extension Routeguide_RouteGuideAsyncClientProtocol {
   public func routeChat<RequestStream>(
     _ requests: RequestStream,
     callOptions: CallOptions? = nil
-  ) -> GRPCAsyncResponseStream<Routeguide_RouteNote> where RequestStream: AsyncSequence, RequestStream.Element == Routeguide_RouteNote {
+  ) -> GRPCAsyncResponseStream<Routeguide_RouteNote> where RequestStream: AsyncSequence & Sendable, RequestStream.Element == Routeguide_RouteNote {
     return self.performAsyncBidirectionalStreamingCall(
       path: Routeguide_RouteGuideClientMetadata.Methods.routeChat.path,
       requests: requests,
diff --git a/Sources/GRPC/AsyncAwaitSupport/AsyncWriter.swift b/Sources/GRPC/AsyncAwaitSupport/AsyncWriter.swift
index fca2620c4..49d85aa7b 100644
--- a/Sources/GRPC/AsyncAwaitSupport/AsyncWriter.swift
+++ b/Sources/GRPC/AsyncAwaitSupport/AsyncWriter.swift
@@ -57,7 +57,7 @@ internal final actor AsyncWriter<Delegate: AsyncWriterDelegate>: Sendable {
   typealias PendingEnd = _Pending<End>
 
   @usableFromInline
-  internal enum _CompletionState {
+  internal enum _CompletionState: Sendable {
     /// Finish hasn't been called yet. May move to `pending` or `completed`.
     case incomplete
     /// Finish has been called but the writer is paused. May move to `completed`.
diff --git a/Sources/GRPC/AsyncAwaitSupport/GRPCAsyncBidirectionalStreamingCall.swift b/Sources/GRPC/AsyncAwaitSupport/GRPCAsyncBidirectionalStreamingCall.swift
index 34bd21b40..af3d71430 100644
--- a/Sources/GRPC/AsyncAwaitSupport/GRPCAsyncBidirectionalStreamingCall.swift
+++ b/Sources/GRPC/AsyncAwaitSupport/GRPCAsyncBidirectionalStreamingCall.swift
@@ -19,7 +19,7 @@ import NIOHPACK
 
 /// Async-await variant of BidirectionalStreamingCall.
 @available(macOS 10.15, iOS 13, tvOS 13, watchOS 6, *)
-public struct GRPCAsyncBidirectionalStreamingCall<Request: Sendable, Response: Sendable> {
+public struct GRPCAsyncBidirectionalStreamingCall<Request: Sendable, Response: Sendable>: Sendable {
   private let call: Call<Request, Response>
   private let responseParts: StreamingResponseParts<Response>
   private let responseSource: PassthroughMessageSource<Response, Error>
diff --git a/Sources/GRPC/AsyncAwaitSupport/GRPCAsyncClientStreamingCall.swift b/Sources/GRPC/AsyncAwaitSupport/GRPCAsyncClientStreamingCall.swift
index ef662ba3e..19c9b3713 100644
--- a/Sources/GRPC/AsyncAwaitSupport/GRPCAsyncClientStreamingCall.swift
+++ b/Sources/GRPC/AsyncAwaitSupport/GRPCAsyncClientStreamingCall.swift
@@ -19,7 +19,7 @@ import NIOHPACK
 
 /// Async-await variant of `ClientStreamingCall`.
 @available(macOS 10.15, iOS 13, tvOS 13, watchOS 6, *)
-public struct GRPCAsyncClientStreamingCall<Request: Sendable, Response: Sendable> {
+public struct GRPCAsyncClientStreamingCall<Request: Sendable, Response: Sendable>: Sendable {
   private let call: Call<Request, Response>
   private let responseParts: UnaryResponseParts<Response>
 
diff --git a/Sources/GRPC/AsyncAwaitSupport/GRPCAsyncRequestStream.swift b/Sources/GRPC/AsyncAwaitSupport/GRPCAsyncRequestStream.swift
index f2beff823..25df9899c 100644
--- a/Sources/GRPC/AsyncAwaitSupport/GRPCAsyncRequestStream.swift
+++ b/Sources/GRPC/AsyncAwaitSupport/GRPCAsyncRequestStream.swift
@@ -52,4 +52,9 @@ public struct GRPCAsyncRequestStream<Element: Sendable>: AsyncSequence {
   }
 }
 
+@available(macOS 10.15, iOS 13, tvOS 13, watchOS 6, *)
+extension GRPCAsyncRequestStream: Sendable where Element: Sendable {}
+@available(macOS 10.15, iOS 13, tvOS 13, watchOS 6, *)
+extension GRPCAsyncRequestStream.Iterator: Sendable where Element: Sendable {}
+
 #endif
diff --git a/Sources/GRPC/AsyncAwaitSupport/GRPCAsyncRequestStreamWriter.swift b/Sources/GRPC/AsyncAwaitSupport/GRPCAsyncRequestStreamWriter.swift
index f1d6c9d66..073fa9d28 100644
--- a/Sources/GRPC/AsyncAwaitSupport/GRPCAsyncRequestStreamWriter.swift
+++ b/Sources/GRPC/AsyncAwaitSupport/GRPCAsyncRequestStreamWriter.swift
@@ -31,7 +31,7 @@
 /// try await stream.finish()
 /// ```
 @available(macOS 10.15, iOS 13, tvOS 13, watchOS 6, *)
-public struct GRPCAsyncRequestStreamWriter<Request: Sendable> {
+public struct GRPCAsyncRequestStreamWriter<Request: Sendable>: Sendable {
   @usableFromInline
   internal let asyncWriter: AsyncWriter<Delegate<Request>>
 
diff --git a/Sources/GRPC/AsyncAwaitSupport/GRPCAsyncResponseStream.swift b/Sources/GRPC/AsyncAwaitSupport/GRPCAsyncResponseStream.swift
index 7a2116aed..a0d1441fd 100644
--- a/Sources/GRPC/AsyncAwaitSupport/GRPCAsyncResponseStream.swift
+++ b/Sources/GRPC/AsyncAwaitSupport/GRPCAsyncResponseStream.swift
@@ -49,4 +49,9 @@ public struct GRPCAsyncResponseStream<Element>: AsyncSequence {
   }
 }
 
+@available(macOS 10.15, iOS 13, tvOS 13, watchOS 6, *)
+extension GRPCAsyncResponseStream: Sendable where Element: Sendable {}
+@available(macOS 10.15, iOS 13, tvOS 13, watchOS 6, *)
+extension GRPCAsyncResponseStream.Iterator: Sendable where Element: Sendable {}
+
 #endif
diff --git a/Sources/GRPC/AsyncAwaitSupport/GRPCAsyncResponseStreamWriter.swift b/Sources/GRPC/AsyncAwaitSupport/GRPCAsyncResponseStreamWriter.swift
index 28e81ca70..454dfa808 100644
--- a/Sources/GRPC/AsyncAwaitSupport/GRPCAsyncResponseStreamWriter.swift
+++ b/Sources/GRPC/AsyncAwaitSupport/GRPCAsyncResponseStreamWriter.swift
@@ -18,7 +18,7 @@
 
 /// Writer for server-streaming RPC handlers to provide responses.
 @available(macOS 10.15, iOS 13, tvOS 13, watchOS 6, *)
-public struct GRPCAsyncResponseStreamWriter<Response: Sendable> {
+public struct GRPCAsyncResponseStreamWriter<Response: Sendable>: Sendable {
   @usableFromInline
   internal typealias Element = (Response, Compression)
 
diff --git a/Sources/GRPC/AsyncAwaitSupport/GRPCAsyncUnaryCall.swift b/Sources/GRPC/AsyncAwaitSupport/GRPCAsyncUnaryCall.swift
index 18f756a44..484f2985c 100644
--- a/Sources/GRPC/AsyncAwaitSupport/GRPCAsyncUnaryCall.swift
+++ b/Sources/GRPC/AsyncAwaitSupport/GRPCAsyncUnaryCall.swift
@@ -22,7 +22,7 @@ import NIOHPACK
 /// Note: while this object is a `struct`, its implementation delegates to `Call`. It therefore
 /// has reference semantics.
 @available(macOS 10.15, iOS 13, tvOS 13, watchOS 6, *)
-public struct GRPCAsyncUnaryCall<Request: Sendable, Response: Sendable> {
+public struct GRPCAsyncUnaryCall<Request: Sendable, Response: Sendable>: Sendable {
   private let call: Call<Request, Response>
   private let responseParts: UnaryResponseParts<Response>
 
diff --git a/Sources/GRPC/AsyncAwaitSupport/GRPCClient+AsyncAwaitSupport.swift b/Sources/GRPC/AsyncAwaitSupport/GRPCClient+AsyncAwaitSupport.swift
index 1169644ef..d60941ef1 100644
--- a/Sources/GRPC/AsyncAwaitSupport/GRPCClient+AsyncAwaitSupport.swift
+++ b/Sources/GRPC/AsyncAwaitSupport/GRPCClient+AsyncAwaitSupport.swift
@@ -19,7 +19,7 @@ import SwiftProtobuf
 
 @available(macOS 10.15, iOS 13, tvOS 13, watchOS 6, *)
 extension GRPCClient {
-  public func makeAsyncUnaryCall<Request: Message, Response: Message>(
+  public func makeAsyncUnaryCall<Request: Message & Sendable, Response: Message & Sendable>(
     path: String,
     request: Request,
     callOptions: CallOptions? = nil,
@@ -34,7 +34,7 @@ extension GRPCClient {
     )
   }
 
-  public func makeAsyncUnaryCall<Request: GRPCPayload, Response: GRPCPayload>(
+  public func makeAsyncUnaryCall<Request: GRPCPayload & Sendable, Response: GRPCPayload & Sendable>(
     path: String,
     request: Request,
     callOptions: CallOptions? = nil,
@@ -50,8 +50,8 @@ extension GRPCClient {
   }
 
   public func makeAsyncServerStreamingCall<
-    Request: SwiftProtobuf.Message,
-    Response: SwiftProtobuf.Message
+    Request: SwiftProtobuf.Message & Sendable,
+    Response: SwiftProtobuf.Message & Sendable
   >(
     path: String,
     request: Request,
@@ -67,7 +67,10 @@ extension GRPCClient {
     )
   }
 
-  public func makeAsyncServerStreamingCall<Request: GRPCPayload, Response: GRPCPayload>(
+  public func makeAsyncServerStreamingCall<
+    Request: GRPCPayload & Sendable,
+    Response: GRPCPayload & Sendable
+  >(
     path: String,
     request: Request,
     callOptions: CallOptions? = nil,
@@ -83,8 +86,8 @@ extension GRPCClient {
   }
 
   public func makeAsyncClientStreamingCall<
-    Request: SwiftProtobuf.Message,
-    Response: SwiftProtobuf.Message
+    Request: SwiftProtobuf.Message & Sendable,
+    Response: SwiftProtobuf.Message & Sendable
   >(
     path: String,
     callOptions: CallOptions? = nil,
@@ -99,7 +102,10 @@ extension GRPCClient {
     )
   }
 
-  public func makeAsyncClientStreamingCall<Request: GRPCPayload, Response: GRPCPayload>(
+  public func makeAsyncClientStreamingCall<
+    Request: GRPCPayload & Sendable,
+    Response: GRPCPayload & Sendable
+  >(
     path: String,
     callOptions: CallOptions? = nil,
     interceptors: [ClientInterceptor<Request, Response>] = [],
@@ -114,8 +120,8 @@ extension GRPCClient {
   }
 
   public func makeAsyncBidirectionalStreamingCall<
-    Request: SwiftProtobuf.Message,
-    Response: SwiftProtobuf.Message
+    Request: SwiftProtobuf.Message & Sendable,
+    Response: SwiftProtobuf.Message & Sendable
   >(
     path: String,
     callOptions: CallOptions? = nil,
@@ -131,8 +137,8 @@ extension GRPCClient {
   }
 
   public func makeAsyncBidirectionalStreamingCall<
-    Request: GRPCPayload,
-    Response: GRPCPayload
+    Request: GRPCPayload & Sendable,
+    Response: GRPCPayload & Sendable
   >(
     path: String,
     callOptions: CallOptions? = nil,
@@ -152,7 +158,7 @@ extension GRPCClient {
 
 @available(macOS 10.15, iOS 13, tvOS 13, watchOS 6, *)
 extension GRPCClient {
-  public func performAsyncUnaryCall<Request: Message, Response: Message>(
+  public func performAsyncUnaryCall<Request: Message & Sendable, Response: Message & Sendable>(
     path: String,
     request: Request,
     callOptions: CallOptions? = nil,
@@ -167,7 +173,10 @@ extension GRPCClient {
     ).response
   }
 
-  public func performAsyncUnaryCall<Request: GRPCPayload, Response: GRPCPayload>(
+  public func performAsyncUnaryCall<
+    Request: GRPCPayload & Sendable,
+    Response: GRPCPayload & Sendable
+  >(
     path: String,
     request: Request,
     callOptions: CallOptions? = nil,
@@ -183,8 +192,8 @@ extension GRPCClient {
   }
 
   public func performAsyncServerStreamingCall<
-    Request: SwiftProtobuf.Message,
-    Response: SwiftProtobuf.Message
+    Request: SwiftProtobuf.Message & Sendable,
+    Response: SwiftProtobuf.Message & Sendable
   >(
     path: String,
     request: Request,
@@ -200,7 +209,10 @@ extension GRPCClient {
     ).responseStream
   }
 
-  public func performAsyncServerStreamingCall<Request: GRPCPayload, Response: GRPCPayload>(
+  public func performAsyncServerStreamingCall<
+    Request: GRPCPayload & Sendable,
+    Response: GRPCPayload & Sendable
+  >(
     path: String,
     request: Request,
     callOptions: CallOptions? = nil,
@@ -216,9 +228,9 @@ extension GRPCClient {
   }
 
   public func performAsyncClientStreamingCall<
-    Request: SwiftProtobuf.Message,
-    Response: SwiftProtobuf.Message,
-    RequestStream
+    Request: SwiftProtobuf.Message & Sendable,
+    Response: SwiftProtobuf.Message & Sendable,
+    RequestStream: AsyncSequence & Sendable
   >(
     path: String,
     requests: RequestStream,
@@ -226,8 +238,7 @@ extension GRPCClient {
     interceptors: [ClientInterceptor<Request, Response>] = [],
     requestType: Request.Type = Request.self,
     responseType: Response.Type = Response.self
-  ) async throws -> Response
-    where RequestStream: AsyncSequence, RequestStream.Element == Request {
+  ) async throws -> Response where RequestStream.Element == Request {
     let call = self.channel.makeAsyncClientStreamingCall(
       path: path,
       callOptions: callOptions ?? self.defaultCallOptions,
@@ -237,9 +248,9 @@ extension GRPCClient {
   }
 
   public func performAsyncClientStreamingCall<
-    Request: GRPCPayload,
-    Response: GRPCPayload,
-    RequestStream
+    Request: GRPCPayload & Sendable,
+    Response: GRPCPayload & Sendable,
+    RequestStream: AsyncSequence & Sendable
   >(
     path: String,
     requests: RequestStream,
@@ -247,8 +258,7 @@ extension GRPCClient {
     interceptors: [ClientInterceptor<Request, Response>] = [],
     requestType: Request.Type = Request.self,
     responseType: Response.Type = Response.self
-  ) async throws -> Response
-    where RequestStream: AsyncSequence, RequestStream.Element == Request {
+  ) async throws -> Response where RequestStream.Element == Request {
     let call = self.channel.makeAsyncClientStreamingCall(
       path: path,
       callOptions: callOptions ?? self.defaultCallOptions,
@@ -258,9 +268,9 @@ extension GRPCClient {
   }
 
   public func performAsyncClientStreamingCall<
-    Request: SwiftProtobuf.Message,
-    Response: SwiftProtobuf.Message,
-    RequestStream
+    Request: SwiftProtobuf.Message & Sendable,
+    Response: SwiftProtobuf.Message & Sendable,
+    RequestStream: Sequence
   >(
     path: String,
     requests: RequestStream,
@@ -268,8 +278,7 @@ extension GRPCClient {
     interceptors: [ClientInterceptor<Request, Response>] = [],
     requestType: Request.Type = Request.self,
     responseType: Response.Type = Response.self
-  ) async throws -> Response
-    where RequestStream: Sequence, RequestStream.Element == Request {
+  ) async throws -> Response where RequestStream.Element == Request {
     let call = self.channel.makeAsyncClientStreamingCall(
       path: path,
       callOptions: callOptions ?? self.defaultCallOptions,
@@ -279,9 +288,9 @@ extension GRPCClient {
   }
 
   public func performAsyncClientStreamingCall<
-    Request: GRPCPayload,
-    Response: GRPCPayload,
-    RequestStream
+    Request: GRPCPayload & Sendable,
+    Response: GRPCPayload & Sendable,
+    RequestStream: Sequence
   >(
     path: String,
     requests: RequestStream,
@@ -289,8 +298,7 @@ extension GRPCClient {
     interceptors: [ClientInterceptor<Request, Response>] = [],
     requestType: Request.Type = Request.self,
     responseType: Response.Type = Response.self
-  ) async throws -> Response
-    where RequestStream: Sequence, RequestStream.Element == Request {
+  ) async throws -> Response where RequestStream.Element == Request {
     let call = self.channel.makeAsyncClientStreamingCall(
       path: path,
       callOptions: callOptions ?? self.defaultCallOptions,
@@ -300,8 +308,8 @@ extension GRPCClient {
   }
 
   public func performAsyncBidirectionalStreamingCall<
-    Request: SwiftProtobuf.Message,
-    Response: SwiftProtobuf.Message,
+    Request: SwiftProtobuf.Message & Sendable,
+    Response: SwiftProtobuf.Message & Sendable,
     RequestStream: AsyncSequence
   >(
     path: String,
@@ -321,8 +329,8 @@ extension GRPCClient {
   }
 
   public func performAsyncBidirectionalStreamingCall<
-    Request: GRPCPayload,
-    Response: GRPCPayload,
+    Request: GRPCPayload & Sendable,
+    Response: GRPCPayload & Sendable,
     RequestStream: AsyncSequence
   >(
     path: String,
@@ -342,8 +350,8 @@ extension GRPCClient {
   }
 
   public func performAsyncBidirectionalStreamingCall<
-    Request: SwiftProtobuf.Message,
-    Response: SwiftProtobuf.Message,
+    Request: SwiftProtobuf.Message & Sendable,
+    Response: SwiftProtobuf.Message & Sendable,
     RequestStream: Sequence
   >(
     path: String,
@@ -352,8 +360,7 @@ extension GRPCClient {
     interceptors: [ClientInterceptor<Request, Response>] = [],
     requestType: Request.Type = Request.self,
     responseType: Response.Type = Response.self
-  ) -> GRPCAsyncResponseStream<Response>
-    where RequestStream.Element == Request {
+  ) -> GRPCAsyncResponseStream<Response> where RequestStream.Element == Request {
     let call = self.channel.makeAsyncBidirectionalStreamingCall(
       path: path,
       callOptions: callOptions ?? self.defaultCallOptions,
@@ -363,8 +370,8 @@ extension GRPCClient {
   }
 
   public func performAsyncBidirectionalStreamingCall<
-    Request: GRPCPayload,
-    Response: GRPCPayload,
+    Request: GRPCPayload & Sendable,
+    Response: GRPCPayload & Sendable,
     RequestStream: Sequence
   >(
     path: String,
@@ -373,8 +380,7 @@ extension GRPCClient {
     interceptors: [ClientInterceptor<Request, Response>] = [],
     requestType: Request.Type = Request.self,
     responseType: Response.Type = Response.self
-  ) -> GRPCAsyncResponseStream<Response>
-    where RequestStream.Element == Request {
+  ) -> GRPCAsyncResponseStream<Response> where RequestStream.Element == Request {
     let call = self.channel.makeAsyncBidirectionalStreamingCall(
       path: path,
       callOptions: callOptions ?? self.defaultCallOptions,
@@ -387,11 +393,14 @@ extension GRPCClient {
 @available(macOS 10.15, iOS 13, tvOS 13, watchOS 6, *)
 extension GRPCClient {
   @inlinable
-  internal func perform<Request, Response, RequestStream>(
+  internal func perform<
+    Request: Sendable,
+    Response: Sendable,
+    RequestStream: AsyncSequence & Sendable
+  >(
     _ call: GRPCAsyncClientStreamingCall<Request, Response>,
     with requests: RequestStream
-  ) async throws -> Response
-    where RequestStream: AsyncSequence, RequestStream.Element == Request {
+  ) async throws -> Response where RequestStream.Element == Request {
     // We use a detached task because we use cancellation to signal early, but successful exit.
     let requestsTask = Task.detached {
       try Task.checkCancellation()
@@ -420,12 +429,14 @@ extension GRPCClient {
   }
 
   @inlinable
-  internal func perform<Request, Response, RequestStream>(
+  internal func perform<
+    Request: Sendable,
+    Response: Sendable,
+    RequestStream: AsyncSequence & Sendable
+  >(
     _ call: GRPCAsyncBidirectionalStreamingCall<Request, Response>,
     with requests: RequestStream
-  )
-    -> GRPCAsyncResponseStream<Response>
-    where RequestStream: AsyncSequence, RequestStream.Element == Request {
+  ) -> GRPCAsyncResponseStream<Response> where RequestStream.Element == Request {
     Task {
       try await withTaskCancellationHandler {
         try Task.checkCancellation()
diff --git a/Sources/GRPC/AsyncAwaitSupport/PassthroughMessageSequence.swift b/Sources/GRPC/AsyncAwaitSupport/PassthroughMessageSequence.swift
index 2dacee55e..31f384a8d 100644
--- a/Sources/GRPC/AsyncAwaitSupport/PassthroughMessageSequence.swift
+++ b/Sources/GRPC/AsyncAwaitSupport/PassthroughMessageSequence.swift
@@ -55,4 +55,9 @@ internal struct PassthroughMessageSequence<Element, Failure: Error>: AsyncSequen
   }
 }
 
+@available(macOS 10.15, iOS 13, tvOS 13, watchOS 6, *)
+extension PassthroughMessageSequence: Sendable where Element: Sendable {}
+@available(macOS 10.15, iOS 13, tvOS 13, watchOS 6, *)
+extension PassthroughMessageSequence.Iterator: Sendable where Element: Sendable {}
+
 #endif // compiler(>=5.6)
diff --git a/Sources/GRPC/AsyncAwaitSupport/PassthroughMessageSource.swift b/Sources/GRPC/AsyncAwaitSupport/PassthroughMessageSource.swift
index 963286558..82b04ced7 100644
--- a/Sources/GRPC/AsyncAwaitSupport/PassthroughMessageSource.swift
+++ b/Sources/GRPC/AsyncAwaitSupport/PassthroughMessageSource.swift
@@ -160,4 +160,8 @@ internal final class PassthroughMessageSource<Element, Failure: Error> {
   }
 }
 
+@available(macOS 10.15, iOS 13, tvOS 13, watchOS 6, *)
+// @unchecked is ok: mutable state is accessed/modified via a lock.
+extension PassthroughMessageSource: @unchecked Sendable where Element: Sendable {}
+
 #endif // compiler(>=5.6)
diff --git a/Sources/GRPC/ClientCalls/Call.swift b/Sources/GRPC/ClientCalls/Call.swift
index b847f3098..9244a1687 100644
--- a/Sources/GRPC/ClientCalls/Call.swift
+++ b/Sources/GRPC/ClientCalls/Call.swift
@@ -37,7 +37,7 @@ import protocol SwiftProtobuf.Message
 ///
 /// Callers are not able to create `Call` objects directly, rather they must be created via an
 /// object conforming to `GRPCChannel` such as `ClientConnection`.
-public class Call<Request, Response> {
+public final class Call<Request, Response> {
   @usableFromInline
   internal enum State {
     /// Idle, waiting to be invoked.
@@ -417,3 +417,8 @@ extension Call {
     self._send(.metadata(self.options.customMetadata), promise: nil)
   }
 }
+
+#if compiler(>=5.6)
+// @unchecked is ok: all mutable state is accessed/modified from the appropriate event loop.
+extension Call: @unchecked Sendable where Request: Sendable, Response: Sendable {}
+#endif
diff --git a/Sources/GRPC/ClientCalls/ResponseContainers.swift b/Sources/GRPC/ClientCalls/ResponseContainers.swift
index c34e2d6d2..e20e14fed 100644
--- a/Sources/GRPC/ClientCalls/ResponseContainers.swift
+++ b/Sources/GRPC/ClientCalls/ResponseContainers.swift
@@ -190,3 +190,9 @@ extension Error {
     }
   }
 }
+
+#if compiler(>=5.6)
+// @unchecked is ok: all mutable state is accessed/modified from an appropriate event loop.
+extension UnaryResponseParts: @unchecked Sendable where Response: Sendable {}
+extension StreamingResponseParts: @unchecked Sendable where Response: Sendable {}
+#endif
diff --git a/Sources/protoc-gen-grpc-swift/Generator-Client+AsyncAwait.swift b/Sources/protoc-gen-grpc-swift/Generator-Client+AsyncAwait.swift
index c11970038..967b81344 100644
--- a/Sources/protoc-gen-grpc-swift/Generator-Client+AsyncAwait.swift
+++ b/Sources/protoc-gen-grpc-swift/Generator-Client+AsyncAwait.swift
@@ -155,7 +155,10 @@ extension Generator {
         let streamsResponses = [.serverStreaming, .bidirectionalStreaming].contains(rpcType)
         let streamsRequests = [.clientStreaming, .bidirectionalStreaming].contains(rpcType)
 
-        let sequenceProtocols = streamsRequests ? ["Sequence", "AsyncSequence"] : [nil]
+        // (protocol, requires sendable)
+        let sequenceProtocols: [(String, Bool)?] = streamsRequests
+          ? [("Sequence", false), ("AsyncSequence", true)]
+          : [nil]
 
         for (j, sequenceProtocol) in sequenceProtocols.enumerated() {
           // Print a new line if this is not the first function in the extension.
@@ -170,8 +173,13 @@ extension Generator {
           let returnType = streamsResponses
             ? Types.responseStream(of: self.methodOutputName)
             : self.methodOutputName
-          let maybeWhereClause = sequenceProtocol.map {
-            "where RequestStream: \($0), RequestStream.Element == \(self.methodInputName)"
+          let maybeWhereClause = sequenceProtocol.map { protocolName, mustBeSendable -> String in
+            let constraints = [
+              "RequestStream: \(protocolName)" + (mustBeSendable ? " & Sendable" : ""),
+              "RequestStream.Element == \(self.methodInputName)",
+            ]
+
+            return "where " + constraints.joined(separator: ", ")
           }
           self.printFunction(
             name: functionName,
diff --git a/Tests/GRPCTests/Codegen/Normalization/normalization.grpc.swift b/Tests/GRPCTests/Codegen/Normalization/normalization.grpc.swift
index 00945c23b..112d29900 100644
--- a/Tests/GRPCTests/Codegen/Normalization/normalization.grpc.swift
+++ b/Tests/GRPCTests/Codegen/Normalization/normalization.grpc.swift
@@ -500,7 +500,7 @@ extension Normalization_NormalizationAsyncClientProtocol {
   internal func ClientStreaming<RequestStream>(
     _ requests: RequestStream,
     callOptions: CallOptions? = nil
-  ) async throws -> Normalization_FunctionName where RequestStream: AsyncSequence, RequestStream.Element == SwiftProtobuf.Google_Protobuf_Empty {
+  ) async throws -> Normalization_FunctionName where RequestStream: AsyncSequence & Sendable, RequestStream.Element == SwiftProtobuf.Google_Protobuf_Empty {
     return try await self.performAsyncClientStreamingCall(
       path: Normalization_NormalizationClientMetadata.Methods.ClientStreaming.path,
       requests: requests,
@@ -524,7 +524,7 @@ extension Normalization_NormalizationAsyncClientProtocol {
   internal func clientStreaming<RequestStream>(
     _ requests: RequestStream,
     callOptions: CallOptions? = nil
-  ) async throws -> Normalization_FunctionName where RequestStream: AsyncSequence, RequestStream.Element == SwiftProtobuf.Google_Protobuf_Empty {
+  ) async throws -> Normalization_FunctionName where RequestStream: AsyncSequence & Sendable, RequestStream.Element == SwiftProtobuf.Google_Protobuf_Empty {
     return try await self.performAsyncClientStreamingCall(
       path: Normalization_NormalizationClientMetadata.Methods.clientStreaming.path,
       requests: requests,
@@ -548,7 +548,7 @@ extension Normalization_NormalizationAsyncClientProtocol {
   internal func BidirectionalStreaming<RequestStream>(
     _ requests: RequestStream,
     callOptions: CallOptions? = nil
-  ) -> GRPCAsyncResponseStream<Normalization_FunctionName> where RequestStream: AsyncSequence, RequestStream.Element == SwiftProtobuf.Google_Protobuf_Empty {
+  ) -> GRPCAsyncResponseStream<Normalization_FunctionName> where RequestStream: AsyncSequence & Sendable, RequestStream.Element == SwiftProtobuf.Google_Protobuf_Empty {
     return self.performAsyncBidirectionalStreamingCall(
       path: Normalization_NormalizationClientMetadata.Methods.BidirectionalStreaming.path,
       requests: requests,
@@ -572,7 +572,7 @@ extension Normalization_NormalizationAsyncClientProtocol {
   internal func bidirectionalStreaming<RequestStream>(
     _ requests: RequestStream,
     callOptions: CallOptions? = nil
-  ) -> GRPCAsyncResponseStream<Normalization_FunctionName> where RequestStream: AsyncSequence, RequestStream.Element == SwiftProtobuf.Google_Protobuf_Empty {
+  ) -> GRPCAsyncResponseStream<Normalization_FunctionName> where RequestStream: AsyncSequence & Sendable, RequestStream.Element == SwiftProtobuf.Google_Protobuf_Empty {
     return self.performAsyncBidirectionalStreamingCall(
       path: Normalization_NormalizationClientMetadata.Methods.bidirectionalStreaming.path,
       requests: requests,