diff --git a/unittests/CppInterOp/TestSharedLib/TestSharedLib.h b/unittests/CppInterOp/TestSharedLib/TestSharedLib.h
index 41fe7f758..8736f64bf 100644
--- a/unittests/CppInterOp/TestSharedLib/TestSharedLib.h
+++ b/unittests/CppInterOp/TestSharedLib/TestSharedLib.h
@@ -1,7 +1,11 @@
 #ifndef UNITTESTS_CPPINTEROP_TESTSHAREDLIB_TESTSHAREDLIB_H
 #define UNITTESTS_CPPINTEROP_TESTSHAREDLIB_TESTSHAREDLIB_H
 
-// Avoid having to mangle/demangle the symbol name in tests.
-extern "C" int ret_zero();
+// Avoid having to mangle/demangle the symbol name in tests
+#ifdef WIN32
+  extern "C" __declspec(dllexport) int ret_zero();
+#else
+  extern "C" int ret_zero();
+#endif
 
 #endif // UNITTESTS_CPPINTEROP_TESTSHAREDLIB_TESTSHAREDLIB_H