diff --git a/src/common/serialization/clap.h b/src/common/serialization/clap.h
index a2504efa..f0979534 100644
--- a/src/common/serialization/clap.h
+++ b/src/common/serialization/clap.h
@@ -26,6 +26,7 @@
 #include "clap/ext/latency.h"
 #include "clap/ext/note-ports.h"
 #include "clap/ext/params.h"
+#include "clap/ext/state.h"
 #include "clap/ext/tail.h"
 #include "clap/host.h"
 #include "clap/plugin-factory.h"
diff --git a/src/common/serialization/clap/ext/state.h b/src/common/serialization/clap/ext/state.h
new file mode 100644
index 00000000..866a76f6
--- /dev/null
+++ b/src/common/serialization/clap/ext/state.h
@@ -0,0 +1,96 @@
+// yabridge: a Wine plugin bridge
+// Copyright (C) 2020-2022 Robbert van der Helm
+//
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more destates.
+//
+// You should have received a copy of the GNU General Public License
+// along with this program.  If not, see <https://www.gnu.org/licenses/>.
+
+#pragma once
+
+#include <clap/ext/state.h>
+
+#include "../../common.h"
+#include "../stream.h"
+
+// Serialization messages for `clap/ext/state.h`
+
+namespace clap {
+namespace ext {
+namespace state {
+
+namespace plugin {
+
+/**
+ * The response to the `clap::ext::state::Save` message defined below.
+ */
+struct SaveResponse {
+    std::optional<clap::stream::Stream> result;
+
+    template <typename S>
+    void serialize(S& s) {
+        s.ext(result, bitsery::ext::InPlaceOptional(),
+              [](S& s, auto& v) { s.object(v); });
+    }
+};
+
+/**
+ * Message struct for `clap_plugin_state::save()`.
+ */
+struct Save {
+    using Response = SaveResponse;
+
+    native_size_t instance_id;
+
+    template <typename S>
+    void serialize(S& s) {
+        s.value8b(instance_id);
+    }
+};
+
+/**
+ * Message struct for `clap_plugin_state::load()`.
+ */
+struct Load {
+    using Response = PrimitiveResponse<bool>;
+
+    native_size_t instance_id;
+    clap::stream::Stream stream;
+
+    template <typename S>
+    void serialize(S& s) {
+        s.value8b(instance_id);
+    }
+};
+
+}  // namespace plugin
+
+namespace host {
+
+/**
+ * Message struct for `clap_host_state::mark_dirty()`.
+ */
+struct MarkDirty {
+    using Response = Ack;
+
+    native_size_t owner_instance_id;
+
+    template <typename S>
+    void serialize(S& s) {
+        s.value8b(owner_instance_id);
+    }
+};
+
+}  // namespace host
+
+}  // namespace state
+}  // namespace ext
+}  // namespace clap