diff --git a/src/alpine_bits_python/alpine_bits_helpers.py b/src/alpine_bits_python/alpine_bits_helpers.py
index 955fa98..27fad1e 100644
--- a/src/alpine_bits_python/alpine_bits_helpers.py
+++ b/src/alpine_bits_python/alpine_bits_helpers.py
@@ -733,14 +733,15 @@ def _process_single_reservation(
         room_stay=[room_stay],
     )
 
+    # Always send md5_unique_id as the primary tracking ID
+    # This is guaranteed to fit in 64 chars and has low collision risk
+    res_id_value = reservation.md5_unique_id
     res_id_source = "website"
-    klick_id = None
 
+    # Determine the source based on available click tracking data (for informational purposes)
     if reservation.fbclid != "":
-        klick_id = str(reservation.fbclid)
         res_id_source = "meta"
     elif reservation.gclid != "":
-        klick_id = str(reservation.gclid)
         res_id_source = "google"
 
     # Get utm_medium if available, otherwise use source
@@ -757,7 +758,7 @@ def _process_single_reservation(
 
     hotel_res_id_data = HotelReservationIdData(
         res_id_type=RESERVATION_ID_TYPE,
-        res_id_value=klick_id,
+        res_id_value=res_id_value,
         res_id_source=res_id_source,
         res_id_source_context=res_id_source_context,
     )
diff --git a/src/alpine_bits_python/conversion_service.py b/src/alpine_bits_python/conversion_service.py
index 67add2f..ea6a74c 100644
--- a/src/alpine_bits_python/conversion_service.py
+++ b/src/alpine_bits_python/conversion_service.py
@@ -814,10 +814,10 @@ class ConversionService:
         advertising_partner: str | None,
         session: AsyncSession | None = None,
     ) -> Reservation | None:
-        """Match reservation by advertising tracking data (fbclid/gclid/utm_campaign).
+        """Match reservation by advertising tracking data (fbclid/gclid/md5_unique_id).
 
         Args:
-            advertising_campagne: Truncated tracking ID
+            advertising_campagne: Tracking ID from PMS (could be truncated click_id or md5_unique_id)
             hotel_id: Hotel ID for filtering
             guest_first_name: Guest first name for disambiguation
             guest_last_name: Guest last name for disambiguation
@@ -831,12 +831,14 @@ class ConversionService:
         """
         if session is None:
             session = self.session
-        # Find reservations where fbclid or gclid starts with the truncated value
+        # Find reservations where:
+        # - fbclid/gclid starts with the advertising_campagne value, OR
+        # - md5_unique_id matches exactly (for direct ID matching)
         query = select(Reservation).where(
             or_(
                 Reservation.fbclid.like(f"{advertising_campagne}%"),
                 Reservation.gclid.like(f"{advertising_campagne}%"),
-                Reservation.utm_campaign.like(f"{advertising_campagne}%"),
+                Reservation.md5_unique_id == advertising_campagne,
             )
         )