diff --git a/linear_regression_series.go b/linear_regression_series.go
index d6e8e7b..f40e13c 100644
--- a/linear_regression_series.go
+++ b/linear_regression_series.go
@@ -49,9 +49,9 @@ func (lrs LinearRegressionSeries) GetLimit() int {
 
 // GetEndIndex returns the effective limit end.
 func (lrs LinearRegressionSeries) GetEndIndex() int {
-	offset := lrs.GetOffset() + lrs.Len()
+	windowEnd := lrs.GetOffset() + lrs.GetLimit()
 	innerSeriesLastIndex := lrs.InnerSeries.Len() - 1
-	return Math.MinInt(offset, innerSeriesLastIndex)
+	return Math.MinInt(windowEnd, innerSeriesLastIndex)
 }
 
 // GetOffset returns the data offset.
diff --git a/polynomial_regression_series.go b/polynomial_regression_series.go
index 8a3cc98..66f615a 100644
--- a/polynomial_regression_series.go
+++ b/polynomial_regression_series.go
@@ -52,9 +52,9 @@ func (prs PolynomialRegressionSeries) GetLimit() int {
 
 // GetEndIndex returns the effective limit end.
 func (prs PolynomialRegressionSeries) GetEndIndex() int {
-	offset := prs.GetOffset() + prs.Len()
+	windowEnd := prs.GetOffset() + prs.GetLimit()
 	innerSeriesLastIndex := prs.InnerSeries.Len() - 1
-	return Math.MinInt(offset, innerSeriesLastIndex)
+	return Math.MinInt(windowEnd, innerSeriesLastIndex)
 }
 
 // GetOffset returns the data offset.