diff --git a/lib/cpp/src/server/TNonblockingServer.h b/lib/cpp/src/server/TNonblockingServer.h
index a26fcc5..da36045 100644
--- a/lib/cpp/src/server/TNonblockingServer.h
+++ b/lib/cpp/src/server/TNonblockingServer.h
@@ -60,7 +60,11 @@
 #endif
 
 #ifndef SOCKOPT_CAST_T
-#define SOCKOPT_CAST_T void
+#   ifndef _WIN32
+#       define SOCKOPT_CAST_T void
+#   else
+#       define SOCKOPT_CAST_T char
+#   endif // _WIN32
 #endif
 
 template<class T>