diff --git a/.github/PULL_REQUEST_TEMPLATE.md b/.github/PULL_REQUEST_TEMPLATE.md
index 4f725be..965f519 100644
--- a/.github/PULL_REQUEST_TEMPLATE.md
+++ b/.github/PULL_REQUEST_TEMPLATE.md
@@ -1,3 +1,10 @@
+Closes #
+
+<!-- Put the issue number after "Closes #" so GitHub closes the issue (and,
+during the hackathon, scores it on the leaderboard) when this PR merges.
+Add one "Closes #N" line per issue. Delete the line only if the PR has no
+issue (e.g. a version bump). -->
+
 **What does this change, and why?**
 
 **Testing**