diff --git a/CHANGELOG.md b/CHANGELOG.md
index 9b69a54..8d2a8df 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -6,7 +6,11 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 and this project adheres to
 [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
-<!--## [Unreleased]-->
+## [Unreleased]
+
+### Fixed
+
+- Fix a problem with error struct generation with some lexicons in `deflexicon`.
 
 ## [0.9.0] - 2026-04-16
 
diff --git a/lib/atex/lexicon.ex b/lib/atex/lexicon.ex
index 72d98d5..120eeb1 100644
--- a/lib/atex/lexicon.ex
+++ b/lib/atex/lexicon.ex
@@ -806,14 +806,11 @@ defmodule Atex.Lexicon do
           {{:., [], [{:__aliases__, [alias: false], [single]}, :t]}, [], []}
 
         multiple ->
-          {:|, [],
-           [
-             {:|, [],
-              Enum.map(multiple, fn atom ->
-                {{:., [], [{:__aliases__, [alias: false], [atom]}, :t]}, [], []}
-              end)},
-             nil
-           ]}
+          multiple
+          |> Enum.map(fn atom ->
+            {{:., [], [{:__aliases__, [alias: false], [atom]}, :t]}, [], []}
+          end)
+          |> then(&join_with_pipe(&1 ++ [nil]))
       end
 
     error_structs =