diff --git a/drm/VSyncWorker.h b/drm/VSyncWorker.h
index f0367ae..f032d79 100644
--- a/drm/VSyncWorker.h
+++ b/drm/VSyncWorker.h
@@ -32,6 +32,9 @@
 
 class VSyncWorker {
  public:
+  using VsyncTimestampCallback = std::function<void(int64_t /*timestamp*/,
+                                                    uint32_t /*period*/)>;
+
   ~VSyncWorker() = default;
 
   auto static CreateInstance(std::shared_ptr<DrmDisplayPipeline> &pipe,
@@ -43,6 +46,9 @@
   // Set the expected vsync period.
   void SetVsyncPeriodNs(uint32_t vsync_period_ns);
 
+  // Set or clear a callback to be fired on vsync.
+  void SetTimestampCallback(std::optional<VsyncTimestampCallback> &&callback);
+
   // Enable vsync timestamp tracking. GetLastVsyncTimestamp will return 0 if
   // vsync tracking is disabled, or if no vsync has happened since it was
   // enabled.
@@ -74,6 +80,7 @@
   uint32_t vsync_period_ns_ = kDefaultVSPeriodNs;
   bool enable_vsync_timestamps_ = false;
   uint32_t last_vsync_timestamp_ = 0;
+  std::optional<VsyncTimestampCallback> callback_;
 
   std::condition_variable cv_;
   std::thread vswt_;