diff --git a/Source/com/Administrator.h b/Source/com/Administrator.h
index cd34302c0..5ce62e758 100644
--- a/Source/com/Administrator.h
+++ b/Source/com/Administrator.h
@@ -401,14 +401,51 @@ namespace RPC {
         }
 
     private:
+        // Convert a ProxyType<IIPC> to ProxyType<InvokeMessage> using
+        // static_cast rather than dynamic_cast.
+        //
+        // On macOS, Apple Clang unconditionally emits typeinfo for
+        // implicit template instantiations as "weak private external"
+        // (hidden), regardless of -fvisibility settings or explicit
+        // visibility annotations.  Apple's libc++ compares typeinfo by
+        // pointer only for hidden symbols (no strcmp fallback like
+        // libstdc++ on Linux), so dynamic_cast across dylib boundaries
+        // fails for template types like IPCMessageType.
+        //
+        // The label check (IIPC::Label() == InvokeMessage::Id()) provides
+        // the same runtime type guarantee that dynamic_cast would, and
+        // static_cast correctly adjusts for the multiple-inheritance
+        // layout (IPCMessageType inherits both IIPC and IReferenceCounted).
         static Core::ProxyType<InvokeMessage> ExtractInvokeMessage(const Core::ProxyType<Core::IIPC>& data)
         {
-            Core::ProxyType<InvokeMessage> message(data);
-            ASSERT(message.IsValid() == true);
+            if (data.IsValid() == false) {
+                return Core::ProxyType<InvokeMessage>();
+            }
+
+            Core::IIPC* raw = const_cast<Core::IIPC*>(data.operator->());
+            ASSERT(raw->Label() == InvokeMessage::Id());
+
+            if (raw->Label() != InvokeMessage::Id()) {
+                return Core::ProxyType<InvokeMessage>();
+            }
+
+            InvokeMessage* message = static_cast<InvokeMessage*>(raw);
             if (message->Parameters().IsValid() == false) {
-                message = Core::ProxyType<InvokeMessage>();
+                return Core::ProxyType<InvokeMessage>();
             }
-            return message;
+            return Core::ProxyType<InvokeMessage>(
+                static_cast<Core::IReferenceCounted&>(*message), *message);
+        }
+        static Core::ProxyType<InvokeMessage> ToInvokeMessage(const Core::ProxyType<Core::IIPC>& data)
+        {
+            if ((data.IsValid() == false) || (data->Label() != InvokeMessage::Id())) {
+                return Core::ProxyType<InvokeMessage>();
+            }
+
+            InvokeMessage* message =
+                static_cast<InvokeMessage*>(const_cast<Core::IIPC*>(data.operator->()));
+            return Core::ProxyType<InvokeMessage>(
+                static_cast<Core::IReferenceCounted&>(*message), *message);
         }
 
     public:
@@ -447,7 +484,7 @@ namespace RPC {
         }
         string Identifier() const override {
             string identifier;
-            Core::ProxyType<InvokeMessage> message(_message);
+            Core::ProxyType<InvokeMessage> message(ToInvokeMessage(_message));
             if (message.IsValid() == false) {
                 identifier = _T("{ \"type\": \"COMRPC\" }");
             }
diff --git a/Source/com/Communicator.cpp b/Source/com/Communicator.cpp
index dca924a2f..7c6ce850d 100644
--- a/Source/com/Communicator.cpp
+++ b/Source/com/Communicator.cpp
@@ -598,7 +598,7 @@ namespace RPC {
         // Message delivered and responded on....
         RPC::AnnounceMessage* announceMessage = static_cast<RPC::AnnounceMessage*>(&element);
 
-        ASSERT(dynamic_cast<RPC::AnnounceMessage*>(&element) != nullptr);
+        ASSERT(element.Label() == RPC::AnnounceMessage::Id());
 
         if (announceMessage->Response().IsSet() == true) {
             string jsonMessagingCategories(announceMessage->Response().MessagingCategories());
diff --git a/Source/com/Communicator.h b/Source/com/Communicator.h
index 089af57e8..1ee90e486 100644
--- a/Source/com/Communicator.h
+++ b/Source/com/Communicator.h
@@ -1558,7 +1558,14 @@ namespace RPC {
             public:
                 void Procedure(Core::IPCChannel& channel, Core::ProxyType<Core::IIPC>& data) override {
 
-                    Core::ProxyType<AnnounceMessage> message(data);
+                    // Use static_cast + label check instead of dynamic_cast
+                    // to avoid cross-dylib RTTI failure on macOS (see
+                    // Administrator.h ExtractInvokeMessage for details).
+                    ASSERT(data.IsValid() && data->Label() == AnnounceMessage::Id());
+                    AnnounceMessage* rawMsg =
+                        static_cast<AnnounceMessage*>(const_cast<Core::IIPC*>(data.operator->()));
+                    Core::ProxyType<AnnounceMessage> message(
+                        static_cast<Core::IReferenceCounted&>(*rawMsg), *rawMsg);
 
                     ASSERT(message.IsValid() == true);
                     ASSERT(dynamic_cast<Client*>(&channel) != nullptr);
@@ -1842,7 +1849,14 @@ POP_WARNING()
             {
                 // Oke, see if we can reference count the IPCChannel
                 Core::ProxyType<Core::IPCChannel> refChannel(channel);
-                Core::ProxyType<RPC::AnnounceMessage> message(data);
+
+                // Use static_cast + label check instead of dynamic_cast
+                // (see Administrator.h ExtractInvokeMessage for rationale).
+                ASSERT(data.IsValid() && data->Label() == RPC::AnnounceMessage::Id());
+                RPC::AnnounceMessage* rawMsg =
+                    static_cast<RPC::AnnounceMessage*>(const_cast<Core::IIPC*>(data.operator->()));
+                Core::ProxyType<RPC::AnnounceMessage> message(
+                    static_cast<Core::IReferenceCounted&>(*rawMsg), *rawMsg);
 
                 ASSERT(refChannel.IsValid());