diff --git a/connections/clients/windows/core_adapter.cc b/connections/clients/windows/core_adapter.cc
index 6338cc7a..ee273d73 100644
--- a/connections/clients/windows/core_adapter.cc
+++ b/connections/clients/windows/core_adapter.cc
@@ -226,7 +226,7 @@ void RejectConnection(connections::Core *pCore, const char *endpoint_id,
 void SendPayload(connections::Core *pCore,
                  // todo(jfcarroll) this is being exported, needs to be
                  // refactored to return a plain old c type
-                 char **endpoint_ids, size_t endpoint_ids_size,
+                 const char **endpoint_ids, size_t endpoint_ids_size,
                  PayloadW payloadw, ResultCallbackW callback) {
   if (pCore == nullptr) {
     return;
diff --git a/connections/clients/windows/core_adapter.h b/connections/clients/windows/core_adapter.h
index 78151261..6ebf5431 100644
--- a/connections/clients/windows/core_adapter.h
+++ b/connections/clients/windows/core_adapter.h
@@ -202,7 +202,7 @@ DLL_API void __stdcall RejectConnection(Core*, const char*, ResultCallbackW);
 //         still occur during transmission (and at different times for
 //         different endpoints), and will be delivered via
 //         PayloadCallback#onPayloadTransferUpdate.
-DLL_API void __stdcall SendPayload(Core*, char**, size_t, PayloadW,
+DLL_API void __stdcall SendPayload(Core*, const char**, size_t, PayloadW,
                                    ResultCallbackW);
 
 // Cancels a Payload currently in-flight to or from remote endpoint(s).
diff --git a/connections/clients/windows/dart/core_adapter_dart.cc b/connections/clients/windows/dart/core_adapter_dart.cc
index 3e96338e..6393f715 100644
--- a/connections/clients/windows/dart/core_adapter_dart.cc
+++ b/connections/clients/windows/dart/core_adapter_dart.cc
@@ -585,7 +585,7 @@ void SendPayloadDart(Core *pCore, const char *endpoint_id,
       PayloadW payload(PayloadW::GenerateId(), payload_dart.data,
                        payload_dart.size);
 
-      std::vector<char *> c_string_array;
+      std::vector<const char *> c_string_array;
 
       std::transform(endpoint_ids.begin(), endpoint_ids.end(),
                      std::back_inserter(c_string_array),
@@ -612,7 +612,7 @@ void SendPayloadDart(Core *pCore, const char *endpoint_id,
       InputFile input_file(file_name_str, payload_dart.size);
       PayloadW payload(input_file);
 
-      std::vector<char *> c_string_array;
+      std::vector<const char *> c_string_array;
 
       std::transform(endpoint_ids.begin(), endpoint_ids.end(),
                      std::back_inserter(c_string_array),