diff --git a/app/vmselect/promql/rollup.go b/app/vmselect/promql/rollup.go
index 95f676475..6c999a93c 100644
--- a/app/vmselect/promql/rollup.go
+++ b/app/vmselect/promql/rollup.go
@@ -704,6 +704,8 @@ func getMaxPrevInterval(scrapeInterval int64) int64 {
 }
 
 func removeCounterResets(values []float64) {
+	// There is no need in handling NaNs here, since they are impossible
+	// on values from vmstorage.
 	if len(values) == 0 {
 		return
 	}
@@ -721,9 +723,7 @@ func removeCounterResets(values []float64) {
 			}
 		}
 		prevValue = v
-		if !decimal.IsStaleNaN(v) {
-			values[i] = v + correction
-		}
+		values[i] = v + correction
 	}
 }