diff --git a/compiler/module_qual.qual_errors.m b/compiler/module_qual.qual_errors.m
index 6bc86a99f..803208042 100644
--- a/compiler/module_qual.qual_errors.m
+++ b/compiler/module_qual.qual_errors.m
@@ -352,6 +352,9 @@ report_invalid_user_inst(_SymName, _Insts, ErrorContext, !Specs) :-
 
 warn_unused_interface_import(ParentModuleName,
         ImportedModuleName - ImportContexts, !Specs) :-
+     UNUSED_IMPORT Harmonize the operation of this predicate with
+    % the operation of maybe_generate_redundant_avail_warnings
+    % in unused_imports.m.
     ImportContexts = one_or_more(HeadContext, TailContexts),
     HeadPieces =
         [words("In module"), qual_sym_name(ParentModuleName), suffix(":"), nl,
diff --git a/compiler/unused_imports.m b/compiler/unused_imports.m
index 371e97685..8dbc8e4b9 100644
--- a/compiler/unused_imports.m
+++ b/compiler/unused_imports.m
@@ -216,6 +216,9 @@ compare_avails(AvailA, AvailB, Result) :-
 maybe_generate_redundant_avail_warnings(_ModuleName, [], _, !Specs).
 maybe_generate_redundant_avail_warnings(ModuleName, [Avail | Avails],
         !.PrevAvails, !Specs) :-
+    % XXX UNUSED_IMPORT Harmonize the operation of this predicate with
+    % the operation of warn_unused_interface_import
+    % in module_qual.qual_errors.m.
     list.foldl(add_msg_if_avail_as_general(ModuleName, Avail), !.PrevAvails,
         [], PrevMsgs),
     (