diff --git a/tools/lint-all b/tools/lint-all
index 0068a1625d..9d72d4e796 100755
--- a/tools/lint-all
+++ b/tools/lint-all
@@ -330,7 +330,9 @@ def build_custom_checkers(by_lang):
         {'pattern': "placeholder='[^{]",
          'description': "`placeholder` value should be translatable."},
         ] # type: RuleList
-    json_rules = [] # type: RuleList # just fix newlines at ends of files
+    json_rules = [] # type: RuleList # fix newlines at ends of files
+    # It is okay that json_rules is empty, because the empty list
+    # ensures we'll still check JSON files for whitespace.
     markdown_rules = markdown_whitespace_rules + prose_style_rules
     txt_rules = whitespace_rules