diff --git a/lib/sparkline_svg/core.ex b/lib/sparkline_svg/core.ex
index f83d227..d9add14 100644
--- a/lib/sparkline_svg/core.ex
+++ b/lib/sparkline_svg/core.ex
@@ -11,7 +11,7 @@ defmodule SparklineSvg.Core do
   @typedoc false
   @typep min_max :: {number(), number()}
 
-  @typedoc "Internal representation of a x value of a point"
+  @typedoc "Internal representation of an x value of a point"
   @type x :: number()
 
   @typedoc "Internal representation of a y value of a point"
@@ -105,7 +105,12 @@ defmodule SparklineSvg.Core do
     end)
   end
 
-  @spec calc_resize_ref_lines(SparklineSvg.ref_lines(), points(), min_max(), SparklineSvg.opts()) ::
+  @spec calc_resize_ref_lines(
+          SparklineSvg.ref_lines(),
+          Datapoint.points(),
+          min_max(),
+          SparklineSvg.opts()
+        ) ::
           SparklineSvg.ref_lines()
   defp calc_resize_ref_lines(ref_lines, datapoints, min_max_y, options) do
     ref_lines
diff --git a/lib/sparkline_svg/datapoint.ex b/lib/sparkline_svg/datapoint.ex
index 6fca78b..0129e94 100644
--- a/lib/sparkline_svg/datapoint.ex
+++ b/lib/sparkline_svg/datapoint.ex
@@ -1,16 +1,17 @@
 defmodule SparklineSvg.Datapoint do
   @moduledoc false
 
-  alias SparklineSvg.Type
+  alias SparklineSvg.Core
   alias SparklineSvg.Datapoint
+  alias SparklineSvg.Type
 
   @typedoc false
   @type points :: list(Datapoint.t())
 
   @typedoc false
   @type t :: %Datapoint{
-          source: SparklineSvg.datapoints(),
-          computed: points()
+          source: Core.point(),
+          computed: Core.point()
         }
   @enforce_keys [:source, :computed]
   defstruct [:source, :computed]
diff --git a/lib/sparkline_svg/reference_line.ex b/lib/sparkline_svg/reference_line.ex
index dfe2d27..e7a65dd 100644
--- a/lib/sparkline_svg/reference_line.ex
+++ b/lib/sparkline_svg/reference_line.ex
@@ -64,7 +64,7 @@ defmodule SparklineSvg.ReferenceLine do
   alias SparklineSvg.ReferenceLine
 
   @typedoc "A reference line function."
-  @type ref_line_function :: (Datapoint.t() -> Core.y())
+  @type ref_line_function :: (Datapoint.points() -> Core.y())
 
   @typedoc false
   @type t :: %ReferenceLine{
@@ -177,7 +177,7 @@ defmodule SparklineSvg.ReferenceLine do
   """
 
   @doc since: "0.4.0"
-  @spec median(Datapoint.t()) :: Core.y()
+  @spec median(Datapoint.points()) :: Core.y()
   def median(datapoints) do
     percentile(50).(datapoints)
   end
@@ -207,6 +207,7 @@ defmodule SparklineSvg.ReferenceLine do
   end
 
   @spec find_interpolated_value(Datapoint.t(), number()) :: Core.y()
+  @spec find_interpolated_value(Datapoint.points(), number()) :: Core.y()
   defp find_interpolated_value(_datapoints, index) when index < 1, do: 0
 
   defp find_interpolated_value(datapoints, index) do