diff --git a/CHANGELOG.md b/CHANGELOG.md
index 11ec004cb6..01da079725 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -3,6 +3,7 @@
 ## main / unreleased
 
 * [FEATURE] Templates: Add urlQueryEscape to template functions. #17403
+* [BUGFIX] TSDB: Register `prometheus_tsdb_sample_ooo_delta` metric properly. #17477
 
 ## 3.7.3 / 2025-10-29
 
diff --git a/tsdb/head.go b/tsdb/head.go
index 2c71977b1a..cf773e82b0 100644
--- a/tsdb/head.go
+++ b/tsdb/head.go
@@ -562,6 +562,7 @@ func newHeadMetrics(h *Head, r prometheus.Registerer) *headMetrics {
 			m.checkpointDeleteTotal,
 			m.checkpointCreationFail,
 			m.checkpointCreationTotal,
+			m.oooHistogram,
 			m.mmapChunksTotal,
 			m.mmapChunkCorruptionTotal,
 			m.snapshotReplayErrorTotal,