diff --git a/include/trajopt/cancellation/Cancellation.h b/include/trajopt/cancellation/Cancellation.h
index 51adca8e..8b65b6e8 100644
--- a/include/trajopt/cancellation/Cancellation.h
+++ b/include/trajopt/cancellation/Cancellation.h
@@ -1,6 +1,7 @@
 #pragma once
 #include <atomic>
+#include "trajopt/SymbolExports.h"
 
 namespace trajopt {
-    std::atomic<int>& GetCancellationFlag();
+    std::atomic<int>& TRAJOPT_DLLEXPOT GetCancellationFlag();
 }
\ No newline at end of file