diff --git a/.github/pull_request_template.md b/.github/pull_request_template.md
new file mode 100644
index 0000000..666bd0c
--- /dev/null
+++ b/.github/pull_request_template.md
@@ -0,0 +1,3 @@
+<!--
+REMINDER: Please target the **oldest** branch of the PHPUnit Polyfills that is affected by this issue.
+-->
diff --git a/.remarkrc b/.remarkrc
index 6bd2305..e31fae7 100644
--- a/.remarkrc
+++ b/.remarkrc
@@ -19,7 +19,7 @@
     "remark-lint-no-duplicate-definitions",
     "remark-lint-no-empty-url",
     "remark-lint-no-file-name-consecutive-dashes",
-    "remark-lint-no-file-name-irregular-characters",
+    ["remark-lint-no-file-name-irregular-characters", "\\.a-zA-Z0-9-_"],
     "remark-lint-no-file-name-outer-dashes",
     "remark-lint-no-heading-like-paragraph",
     "remark-lint-no-literal-urls",