diff --git a/spec/models/concerns/siret_champ_etablissement_fetchable_concern_spec.rb b/spec/models/concerns/siret_champ_etablissement_fetchable_concern_spec.rb
index f0cf12fd1..c0abba6e5 100644
--- a/spec/models/concerns/siret_champ_etablissement_fetchable_concern_spec.rb
+++ b/spec/models/concerns/siret_champ_etablissement_fetchable_concern_spec.rb
@@ -1,4 +1,7 @@
-# frozen_string_literal: true
+# frozen_string_literal: false
+
+# The 'siret' variables are literal here and mutated (normalized), so we cannot use frozen siret strings.
+# For simplicity, frozen strings are disabled in this entire file.
 
 RSpec.describe SiretChampEtablissementFetchableConcern do
   describe '.fetch_etablissement!' do