diff --git a/db/migrations/20260719005427_add_album_replaygain.go b/db/migrations/20260719005427_add_album_replaygain.go
index 79c8b8b3e..7f5665947 100644
--- a/db/migrations/20260719005427_add_album_replaygain.go
+++ b/db/migrations/20260719005427_add_album_replaygain.go
@@ -12,28 +12,25 @@ func init() {
 }
 
 func upAddAlbumReplaygain(ctx context.Context, tx *sql.Tx) error {
-	// Backfill the most-frequent non-null value per album, matching MediaFiles.ToAlbum. A plain
-	// max() would pick a minority outlier, and GetTouchedAlbums never re-derives an unchanged album,
-	// so a wrong value would persist. The CTEs group media_file once instead of scanning it per album.
+	// Backfill the most-frequent value per album (matching MediaFiles.ToAlbum), staging RG-bearing rows
+	// into an indexed temp table — a correlated subquery over a windowed CTE re-scans media_file per album.
 	_, err := tx.ExecContext(ctx, `
 ALTER TABLE album ADD COLUMN rg_album_gain real;
 ALTER TABLE album ADD COLUMN rg_album_peak real;
 
-WITH gain_mode AS (
-	SELECT album_id, rg_album_gain AS val,
-		row_number() OVER (PARTITION BY album_id ORDER BY count(*) DESC, rg_album_gain) AS rn
-	FROM media_file WHERE rg_album_gain IS NOT NULL
-	GROUP BY album_id, rg_album_gain
-),
-peak_mode AS (
-	SELECT album_id, rg_album_peak AS val,
-		row_number() OVER (PARTITION BY album_id ORDER BY count(*) DESC, rg_album_peak) AS rn
-	FROM media_file WHERE rg_album_peak IS NOT NULL
-	GROUP BY album_id, rg_album_peak
-)
+CREATE TEMP TABLE _rg_backfill AS
+	SELECT album_id, rg_album_gain, rg_album_peak FROM media_file
+	WHERE rg_album_gain IS NOT NULL OR rg_album_peak IS NOT NULL;
+CREATE INDEX _rg_backfill_album ON _rg_backfill(album_id);
+
 UPDATE album SET
-	rg_album_gain = (SELECT val FROM gain_mode WHERE gain_mode.album_id = album.id AND gain_mode.rn = 1),
-	rg_album_peak = (SELECT val FROM peak_mode WHERE peak_mode.album_id = album.id AND peak_mode.rn = 1);
+	rg_album_gain = (SELECT rg_album_gain FROM _rg_backfill WHERE _rg_backfill.album_id = album.id AND rg_album_gain IS NOT NULL
+		GROUP BY rg_album_gain ORDER BY count(*) DESC, rg_album_gain LIMIT 1),
+	rg_album_peak = (SELECT rg_album_peak FROM _rg_backfill WHERE _rg_backfill.album_id = album.id AND rg_album_peak IS NOT NULL
+		GROUP BY rg_album_peak ORDER BY count(*) DESC, rg_album_peak LIMIT 1)
+WHERE album.id IN (SELECT album_id FROM _rg_backfill);
+
+DROP TABLE _rg_backfill;
 	`)
 	return err
 }