diff --git a/lib/isc/win32/libisc.def b/lib/isc/win32/libisc.def
index e828ae3c55..ccc1c4edbb 100644
--- a/lib/isc/win32/libisc.def
+++ b/lib/isc/win32/libisc.def
@@ -316,7 +316,7 @@ isc_portset_add
 isc_portset_addrange
 isc_portset_create
 isc_portset_destroy
-isc_portset_issset
+isc_portset_isset
 isc_portset_nports
 isc_portset_remove
 isc_portset_removerange