diff --git a/icmd/internal/stub/main.go b/icmd/internal/stub/main.go
index a7fa1fd8..77395f47 100644
--- a/icmd/internal/stub/main.go
+++ b/icmd/internal/stub/main.go
@@ -1,3 +1,4 @@
+// Package main produces a test-binary used in tests.
 package main
 
 import (
diff --git a/internal/format/diff.go b/internal/format/diff.go
index 9897d4b9..4f6c07a3 100644
--- a/internal/format/diff.go
+++ b/internal/format/diff.go
@@ -1,3 +1,4 @@
+// Package format provides utilities for formatting diffs and messages.
 package format
 
 import (
diff --git a/internal/maint/maint.go b/internal/maint/maint.go
index 6d6a7cff..c4e85882 100644
--- a/internal/maint/maint.go
+++ b/internal/maint/maint.go
@@ -1,3 +1,5 @@
+// Package maint implements assert.TestingT for uses outside of test cases,
+// for example, in a TestMain.
 package maint // import "gotest.tools/v3/internal/maint"
 
 import (