diff --git a/doc/contributing/collaborator-guide.md b/doc/contributing/collaborator-guide.md
index b19511bcda5f10..3856b876112224 100644
--- a/doc/contributing/collaborator-guide.md
+++ b/doc/contributing/collaborator-guide.md
@@ -356,7 +356,7 @@ Existing stable public APIs that change in a backward-incompatible way must
 undergo deprecation. The exceptions to this rule are:
 
 * Adding or removing errors thrown or reported by a public API.
-* Emitting a warning
+* Emitting a warning.
 * Changing error messages for errors without error code.
 * Altering the timing and non-internal side effects of the public API.
 * Changes to errors thrown by dependencies of Node.js, such as V8.