diff --git a/src/acquisition.cpp b/src/acquisition.cpp
index 5da82b8..bad35a9 100644
--- a/src/acquisition.cpp
+++ b/src/acquisition.cpp
@@ -900,9 +900,13 @@ void Acquisition::backfill_from(const udps_frame_t* frame, const Partition& part
   // and resequencing are one design. A stamp could not answer it -- the packet's own stamps
   // are a claim about a timeline the ring has moved past -- but the counter indexes the
   // reservation table directly.
+  // By signed delta, the idiom the client uses throughout: the counter is a wrapping uint32, so
+  // a raw `>=`/`<` pair matches nothing for a hole straddling the 2^32 wrap and every one of its
+  // late packets would be dropped on the next line.
   Hole* hole = nullptr;
   for (Hole& h : model_.holes()) {
-    if (frame->counter >= h.counter_first && frame->counter < h.counter_first + h.packets) {
+    const std::int32_t into = static_cast<std::int32_t>(frame->counter - h.counter_first);
+    if (into >= 0 && into < static_cast<std::int32_t>(h.packets)) {
       hole = &h;
       break;
     }