diff --git a/src/pipewire/core.c b/src/pipewire/core.c
index 48931a017..2fe0eb79e 100644
--- a/src/pipewire/core.c
+++ b/src/pipewire/core.c
@@ -476,6 +476,12 @@ struct pw_mempool * pw_core_get_mempool(struct pw_core *core)
 SPA_EXPORT
 int pw_core_disconnect(struct pw_core *core)
 {
+	/*
+	 * the `proxy` member must be the first because the whole pw_core object is
+	 * freed via the free() call in pw_proxy_destroy() -> pw_proxy_unref()
+	 */
+	SPA_STATIC_ASSERT(offsetof(struct pw_core, proxy) == 0, "`proxy` member must be first");
+
 	pw_log_debug("%p: disconnect", core);
 	if (!core->removed)
 		pw_proxy_remove(&core->proxy);