diff --git a/src/core/iomgr/pollset_set_windows.h b/src/core/iomgr/pollset_set_windows.h
index ec3d57d9c42..0f91f1ede7c 100644
--- a/src/core/iomgr/pollset_set_windows.h
+++ b/src/core/iomgr/pollset_set_windows.h
@@ -35,6 +35,7 @@
 #define GRPC_INTERNAL_CORE_IOMGR_POLLSET_SET_WINDOWS_H
 
 typedef struct grpc_pollset_set {
+	void *unused;
 } grpc_pollset_set;
 
 #endif /* GRPC_INTERNAL_CORE_IOMGR_POLLSET_WINDOWS_H */