diff --git a/lib/isc/win32/libisc.def.in b/lib/isc/win32/libisc.def.in
index 3c4dd02f71..e6f7787291 100644
--- a/lib/isc/win32/libisc.def.in
+++ b/lib/isc/win32/libisc.def.in
@@ -101,6 +101,7 @@ isc_socketmgr_setreserved
 isc_socketmgr_setstats
 isc_task_getname
 isc_task_gettag
+isc_task_ready
 isc_task_run
 isc_task_unsendrange
 isc_taskmgr_attach