diff --git a/libos/src/EventLoop.cpp b/libos/src/EventLoop.cpp
index acc042fc..d7af3266 100644
--- a/libos/src/EventLoop.cpp
+++ b/libos/src/EventLoop.cpp
@@ -44,6 +44,7 @@ namespace os
         return *s_the;
     }
 
+    // FIXME: Support lambdas (by using os::Action). This means that os::Action needs variable parameter support.
     Result<void> EventLoop::register_fd_listener(int fd, void (*listener)(int, int))
     {
         TRY(m_fd_listeners.try_set(fd, listener));