diff --git a/include/mp/proxy-io.h b/include/mp/proxy-io.h
index 1e27f96..e74a5ee 100644
--- a/include/mp/proxy-io.h
+++ b/include/mp/proxy-io.h
@@ -15,6 +15,7 @@
 #include <capnp/rpc-twoparty.h>
 
 #include <functional>
+#include <memory>
 #include <string>
 
 namespace mp {
@@ -199,7 +200,7 @@ class EventLoop
     LoggingErrorHandler m_error_handler{*this};
 
     //! Capnp list of pending promises.
-    boost::optional<kj::TaskSet> m_task_set;
+    std::unique_ptr<kj::TaskSet> m_task_set;
 
     //! List of connections.
     std::list<Connection> m_incoming_connections;
diff --git a/src/mp/proxy.cpp b/src/mp/proxy.cpp
index 8b0c2b0..e1ae9b8 100644
--- a/src/mp/proxy.cpp
+++ b/src/mp/proxy.cpp
@@ -123,13 +123,16 @@ void Connection::addAsyncCleanup(std::function<void()> fn)
 }
 
 EventLoop::EventLoop(const char* exe_name, LogFn log_fn, void* context)
-    : m_exe_name(exe_name), m_io_context(kj::setupAsyncIo()), m_log_fn(std::move(log_fn)), m_context(context)
+    : m_exe_name(exe_name),
+      m_io_context(kj::setupAsyncIo()),
+      m_log_fn(std::move(log_fn)),
+      m_context(context),
+      m_task_set(new kj::TaskSet(m_error_handler))
 {
     int fds[2];
     KJ_SYSCALL(socketpair(AF_UNIX, SOCK_STREAM, 0, fds));
     m_wait_fd = fds[0];
     m_post_fd = fds[1];
-    m_task_set.emplace(m_error_handler);
 }
 
 EventLoop::~EventLoop()