diff --git a/Makefile b/Makefile
index c024074..72a4f6a 100644
--- a/Makefile
+++ b/Makefile
@@ -7,7 +7,7 @@ build: instructions
 
 run: instructions
 	cd ./src/github_projects_burndown_chart \
-	&& PYTHONPATH=. python main.py $(project_type) $(project_name)
+	&& PYTHONPATH=. python main.py $(type) $(name)
 
 test: instructions
 	coverage run \
diff --git a/README.md b/README.md
index db209d2..3ebc65d 100644
--- a/README.md
+++ b/README.md
@@ -88,6 +88,7 @@ This allows the `.gitignore` to exclude your `config.json` from being accidental
 |----------|---------|
 | `sprint_start_date` | The first day of the sprint formatted as `YYYY-MM-DD`. <br/><br/> Must be entered here since GitHub Project Boards don't have an assigned start/end date. <br/><br/> Example: `2021-10-08` |
 | `sprint_end_date` | The last day of the sprint formatted as `YYYY-MM-DD`. <br/><br/> Must be entered here since GitHub Project Boards don't have an assigned start/end date. <br/><br/> Example: `2021-10-21` |
+| `chart_end_date` | (OPTIONAL) The last day to show on the burndown chart formatted as `YYYY-MM-DD`. <br/><br/> Used to change the end date of the chart without affecting the slope of the ideal burndown line (e.g. to show tasks that were completed after the official end of a sprint). <br/><br/> Example: `2021-10-24` |
 | `points_label` | (OPTIONAL) The prefix for issue labels containing the point value of the issue. Removing this prefix must leave just an integer. If set to `null`, the burndown chart will count open issues instead of points.<br/><br/> Example: `Points: ` (with the space) |
 
 #### Organization Projects
@@ -100,7 +101,7 @@ All settings are the same as for the [Repository Projects](#repository-projects)
 ## Usage
 Given that `PROJECT_TYPE` is one of `[repository, organization]` and `PROJECT_NAME` matches a key in the `config.json` under the chosen `PROJECT_TYPE`, run the following command:
 ```
-make run project_type=PROJECT_TYPE project_name=PROJECT_NAME
+make run type=PROJECT_TYPE name=PROJECT_NAME
 ```
 
 This will pop up an interactive window containing the burndown chart, including a button for saving it as a picture.
@@ -110,12 +111,12 @@ Make a copy of `example.config.json` without the leading `example.`
 
 To see this repository's example project board:
 ```
-make run project_type=repository project_name=burndown_chart_kickoff
+make run type=repository name=burndown_chart_kickoff
 ```
 
 To see Golang's progress on their current roadmap:
 ```
-make run project_type=organization project_name=golang_on_deck
+make run type=organization name=golang_on_deck
 ```
 
 ## Contributing
diff --git a/src/github_projects_burndown_chart/chart/burndown.py b/src/github_projects_burndown_chart/chart/burndown.py
index e1e6101..414c193 100644
--- a/src/github_projects_burndown_chart/chart/burndown.py
+++ b/src/github_projects_burndown_chart/chart/burndown.py
@@ -13,21 +13,26 @@ def __init__(self, project: Project):
             config['settings']['sprint_start_date'])
         self.end_date_utc: datetime = parse_to_utc(
             config['settings']['sprint_end_date'])
+        self.chart_end_date_utc: datetime = parse_to_utc(
+            config['settings']['chart_end_date']) \
+                if config['settings'].get('chart_end_date') else None
 
         self.project: Project = project
 
     def render(self):
+        end_date = self.chart_end_date_utc if self.chart_end_date_utc else self.end_date_utc
         outstanding_points_by_day = self.project.outstanding_points_by_date(
             self.start_date_utc,
-            self.end_date_utc)
+            end_date)
         # Load date dict for priority values with x being range of how many days are in sprint
         x = list(range(len(outstanding_points_by_day.keys())))
         y = list(outstanding_points_by_day.values())
+        sprint_days = (self.end_date_utc - self.start_date_utc).days
 
         # Plot point values for sprint along xaxis=range yaxis=points over time
         plt.plot(x, y)
         plt.axline((x[0], self.project.total_points),
-                   slope=-(self.project.total_points/(len(y)-1)),
+                   slope=-(self.project.total_points/(sprint_days)),
                    color="green",
                    linestyle=(0, (5, 5)))