diff --git a/shared/DeckLinkSender.hpp b/shared/DeckLinkSender.hpp
index 21ab7ca..75d3aff 100644
--- a/shared/DeckLinkSender.hpp
+++ b/shared/DeckLinkSender.hpp
@@ -110,7 +110,6 @@ public:
         // Create frame pool. Frames start in free_frames; submit_frame() schedules
         // them as live content arrives. StartScheduledPlayback is deferred until
         // kPreroll frames have been scheduled so the card has a buffer to draw from.
-        constexpr size_t kPreroll = 3;
         for (size_t i = 0; i < kPreroll; ++i) {
             IDeckLinkMutableVideoFrame* vf = nullptr;
             r = decklink_output->CreateVideoFrame(
@@ -221,6 +220,8 @@ private:
     std::condition_variable              pool_cv;
     std::vector<IDeckLinkMutableVideoFrame*> free_frames;
 
+    static constexpr size_t kPreroll = 3;
+
     // Scheduling state — only written from submit_frame/submit_audio (single-threaded caller)
     bool                 playback_started_ = false;
     size_t               frames_scheduled_ = 0;