diff --git a/changes/bug23081 b/changes/bug23081
new file mode 100644
index 0000000000..76c4e30971
--- /dev/null
+++ b/changes/bug23081
@@ -0,0 +1,8 @@
+  o Minor bugfixes (Windows service):
+    - When running as a Windows service, set the ID of the main thread
+      correctly. Failure to do so made us fail to send log messages
+      to the controller in 0.2.1.16-rc, slowed down controller
+      event delivery in 0.2.7.3-rc and later, and crash with an assertion
+      failure in 0.3.1.1-alpha. Fixes bug 23081; bugfix on 0.2.1.6-alpha.
+      Patch and diagnosis from "Vort".
+
diff --git a/src/or/ntmain.c b/src/or/ntmain.c
index e087bd6937..d0d5276c48 100644
--- a/src/or/ntmain.c
+++ b/src/or/ntmain.c
@@ -293,6 +293,7 @@ nt_service_body(int argc, char **argv)
    * event loop */
   service_status.dwCurrentState = SERVICE_RUNNING;
   service_fns.SetServiceStatus_fn(hStatus, &service_status);
+  set_main_thread();
   do_main_loop();
   tor_cleanup();
 }