diff --git a/chart_test.go b/chart_test.go
index a14a60c..6a04793 100644
--- a/chart_test.go
+++ b/chart_test.go
@@ -505,8 +505,8 @@ func TestChartE2ELine(t *testing.T) {
 		},
 		Series: []Series{
 			ContinuousSeries{
-				XValues: sequence.Values(0, 4, 1),
-				YValues: sequence.Values(0, 4, 1),
+				XValues: sequence.ValuesWithStep(0, 4, 1),
+				YValues: sequence.ValuesWithStep(0, 4, 1),
 			},
 		},
 	}
@@ -550,8 +550,8 @@ func TestChartE2ELineWithFill(t *testing.T) {
 					StrokeColor: drawing.ColorBlue,
 					FillColor:   drawing.ColorRed,
 				},
-				XValues: sequence.Values(0, 4, 1),
-				YValues: sequence.Values(0, 4, 1),
+				XValues: sequence.ValuesWithStep(0, 4, 1),
+				YValues: sequence.ValuesWithStep(0, 4, 1),
 			},
 		},
 	}
diff --git a/sequence/linear.go b/sequence/linear.go
index 71f4ffa..ea703b9 100644
--- a/sequence/linear.go
+++ b/sequence/linear.go
@@ -24,7 +24,7 @@ type Linear struct {
 
 // Len returns the number of elements in the sequence.
 func (lg Linear) Len() int {
-	return int((lg.limit - lg.offset) / lg.step)
+	return (int((lg.limit - lg.offset) / lg.step)) + 1
 }
 
 // GetValue returns the value at a given index.
diff --git a/sequence/linear_test.go b/sequence/linear_test.go
new file mode 100644
index 0000000..d3c7e21
--- /dev/null
+++ b/sequence/linear_test.go
@@ -0,0 +1,24 @@
+package sequence
+
+import (
+	"testing"
+
+	assert "github.com/blendlabs/go-assert"
+)
+
+func TestValues(t *testing.T) {
+	assert := assert.New(t)
+
+	values := Values(1, 100)
+	assert.Len(values, 100)
+	assert.Equal(1, values[0])
+	assert.Equal(100, values[99])
+}
+
+func TestValueWithStep(t *testing.T) {
+	assert := assert.New(t)
+
+	values := ValuesWithStep(0, 100, 5)
+	assert.Equal(100, values[20])
+	assert.Len(values, 21)
+}
diff --git a/sma_series_test.go b/sma_series_test.go
index b416698..6c110f4 100644
--- a/sma_series_test.go
+++ b/sma_series_test.go
@@ -21,7 +21,7 @@ func (m mockValuesProvider) GetValues(index int) (x, y float64) {
 	if index < 0 {
 		panic("negative index at GetValue()")
 	}
-	if index > util.Math.MinInt(len(m.X), len(m.Y)) {
+	if index >= util.Math.MinInt(len(m.X), len(m.Y)) {
 		panic("index is outside the length of m.X or m.Y")
 	}
 	x = m.X[index]