diff --git a/libuavcan/include/uavcan/service_client.hpp b/libuavcan/include/uavcan/service_client.hpp
index bc42b5eff6..9e0e07a99b 100644
--- a/libuavcan/include/uavcan/service_client.hpp
+++ b/libuavcan/include/uavcan/service_client.hpp
@@ -88,13 +88,14 @@ private:
             handleFatalError("Invalid caller callback");
     }
 
-    void handleReceivedDataStruct(ReceivedDataStructure<ResponseType>& request)
+    void handleReceivedDataStruct(ReceivedDataStructure<ResponseType>& response)
     {
+        assert(response.getTransferType() == TransferTypeServiceResponse);
         const TransferListenerType* const listener = SubscriberType::getTransferListener();
         if (listener)
         {
             const typename TransferListenerType::ExpectedResponseParams erp = listener->getExpectedResponseParams();
-            ServiceCallResultType result(ServiceCallResultType::Success, erp.src_node_id, request);
+            ServiceCallResultType result(ServiceCallResultType::Success, erp.src_node_id, response);
             cancel();
             invokeCallback(result);
         }
diff --git a/libuavcan/include/uavcan/service_server.hpp b/libuavcan/include/uavcan/service_server.hpp
index a3f37500c1..cbe8e436ff 100644
--- a/libuavcan/include/uavcan/service_server.hpp
+++ b/libuavcan/include/uavcan/service_server.hpp
@@ -38,6 +38,7 @@ private:
 
     void handleReceivedDataStruct(ReceivedDataStructure<RequestType>& request)
     {
+        assert(request.getTransferType() == TransferTypeServiceRequest);
         if (try_implicit_cast<bool>(callback_, true))
         {
             response_ = ResponseType();  // The application needs newly initialized structure