diff --git a/README.md b/README.md
index 980b73330..de41a4a30 100644
--- a/README.md
+++ b/README.md
@@ -1767,6 +1767,9 @@ This aligns with the [staleness rules in Prometheus](https://prometheus.io/docs/
 If multiple raw samples have **the same timestamp** on the given `-dedup.minScrapeInterval` discrete interval, 
 then the sample with **the biggest value** is kept.
 
+Prometheus stale markers are respected as any other value. If raw sample with the biggest timestamp on `-dedup.minScrapeInterval`
+has a stale marker as a value - it will be kept after the deduplication.
+
 Please note, [labels](https://docs.victoriametrics.com/keyConcepts.html#labels) of raw samples should be identical
 in order to be deduplicated. For example, this is why [HA pair of vmagents](https://docs.victoriametrics.com/vmagent.html#high-availability)
 needs to be identically configured. 
diff --git a/lib/storage/dedup.go b/lib/storage/dedup.go
index 9f8e45369..dcdefbfd8 100644
--- a/lib/storage/dedup.go
+++ b/lib/storage/dedup.go
@@ -25,6 +25,8 @@ func isDedupEnabled() bool {
 }
 
 // DeduplicateSamples removes samples from src* if they are closer to each other than dedupInterval in milliseconds.
+// DeduplicateSamples treats StaleNaN (Prometheus stale markers) as values and doesn't skip them on purpose - see
+// https://github.com/VictoriaMetrics/VictoriaMetrics/issues/5587
 func DeduplicateSamples(srcTimestamps []int64, srcValues []float64, dedupInterval int64) ([]int64, []float64) {
 	if !needsDedup(srcTimestamps, dedupInterval) {
 		// Fast path - nothing to deduplicate