diff --git a/libs/pbd/event_loop.cc b/libs/pbd/event_loop.cc
index 424636feda..3f5eeb0a75 100644
--- a/libs/pbd/event_loop.cc
+++ b/libs/pbd/event_loop.cc
@@ -222,7 +222,7 @@ EventLoop::pre_register (const string& emitting_thread_name, uint32_t num_reques
 void
 EventLoop::remove_request_buffer_from_map (void* ptr)
 {
-	Glib::Threads::RWLock::ReaderLock lm (thread_buffer_requests_lock);
+	Glib::Threads::RWLock::WriterLock lm (thread_buffer_requests_lock);
 
 	for (ThreadRequestBufferList::iterator x = thread_buffer_requests.begin(); x != thread_buffer_requests.end(); ++x) {
 		if (x->second.request_buffer == ptr) {