diff --git a/src/runtime/interrupt.cpp b/src/runtime/interrupt.cpp
index b66fd0c8d8..903f665a11 100644
--- a/src/runtime/interrupt.cpp
+++ b/src/runtime/interrupt.cpp
@@ -42,7 +42,7 @@ void check_heartbeat() {
 
 LEAN_THREAD_VALUE(lean_object *, g_cancel_tk, nullptr);
 
-scope_cancel_tk::scope_cancel_tk(lean_object * o):flet<lean_object *>(g_cancel_tk, o) {}
+LEAN_EXPORT scope_cancel_tk::scope_cancel_tk(lean_object * o):flet<lean_object *>(g_cancel_tk, o) {}
 
 /* CancelToken.isSet : @& IO.CancelToken → BaseIO Bool */
 extern "C" lean_obj_res lean_io_cancel_token_is_set(b_lean_obj_arg cancel_tk, lean_obj_arg);
diff --git a/src/runtime/interrupt.h b/src/runtime/interrupt.h
index 055363d057..14cf99385b 100644
--- a/src/runtime/interrupt.h
+++ b/src/runtime/interrupt.h
@@ -43,9 +43,9 @@ public:
 LEAN_EXPORT void check_heartbeat();
 
 /* Update the thread local `IO.CancelToken` (`nullptr` if unset) */
-class scope_cancel_tk : flet<lean_object *> {
+class LEAN_EXPORT scope_cancel_tk : flet<lean_object *> {
 public:
-    scope_cancel_tk(lean_object *);
+    LEAN_EXPORT scope_cancel_tk(lean_object *);
 };
 
 /**