diff --git a/app/vmselect/promql/exec_test.go b/app/vmselect/promql/exec_test.go
index f05b043ace..af5d976d8d 100644
--- a/app/vmselect/promql/exec_test.go
+++ b/app/vmselect/promql/exec_test.go
@@ -4836,7 +4836,7 @@ func TestExecSuccess(t *testing.T) {
 		q := `integrate(time()/1e3)`
 		r := netstorage.Result{
 			MetricName: metricNameExpected,
-			Values:     []float64{180, 220.00000000000003, 259.99999999999994, 300, 340.00000000000006, 380},
+			Values:     []float64{160, 200, 240, 280, 320, 360},
 			Timestamps: timestampsExpected,
 		}
 		resultExpected := []netstorage.Result{r}
diff --git a/app/vmselect/promql/rollup.go b/app/vmselect/promql/rollup.go
index a271757b18..16087c052e 100644
--- a/app/vmselect/promql/rollup.go
+++ b/app/vmselect/promql/rollup.go
@@ -1710,7 +1710,7 @@ func rollupIntegrate(rfa *rollupFuncArg) float64 {
 	for i, v := range values {
 		timestamp := timestamps[i]
 		dt := float64(timestamp-prevTimestamp) / 1e3
-		sum += 0.5 * (v + prevValue) * dt
+		sum += prevValue * dt
 		prevTimestamp = timestamp
 		prevValue = v
 	}
diff --git a/app/vmselect/promql/rollup_test.go b/app/vmselect/promql/rollup_test.go
index d8080685a8..aef7c335f6 100644
--- a/app/vmselect/promql/rollup_test.go
+++ b/app/vmselect/promql/rollup_test.go
@@ -431,7 +431,7 @@ func TestRollupNewRollupFuncSuccess(t *testing.T) {
 	f("stdvar_over_time", 945.7430555555555)
 	f("first_over_time", 123)
 	f("last_over_time", 34)
-	f("integrate", 5.4705)
+	f("integrate", 5.237)
 	f("distinct_over_time", 8)
 	f("ideriv", 0)
 	f("decreases_over_time", 5)
@@ -970,7 +970,7 @@ func TestRollupFuncsNoWindow(t *testing.T) {
 		}
 		rc.Timestamps = getTimestamps(rc.Start, rc.End, rc.Step)
 		values := rc.Do(nil, testValues, testTimestamps)
-		valuesExpected := []float64{nan, 1.526, 2.2795, 1.325, 0.34}
+		valuesExpected := []float64{nan, 2.064, 1.677, 1.156, 0.34}
 		timestampsExpected := []int64{0, 40, 80, 120, 160}
 		testRowsEqual(t, values, rc.Timestamps, valuesExpected, timestampsExpected)
 	})