diff --git a/app/services/api_geo_service.rb b/app/services/api_geo_service.rb
index 19931cc19..06e1cb094 100644
--- a/app/services/api_geo_service.rb
+++ b/app/services/api_geo_service.rb
@@ -81,9 +81,11 @@ class APIGeoService
     end
 
     def communes_by_postal_code(postal_code)
-      communes_by_postal_code_map.fetch(postal_code, [])
-        .filter { !_1[:code].in?(['75056', '13055', '69123']) }
-        .sort_by { I18n.transliterate([_1[:name], _1[:postal_code]].join(' ')) }
+      Rails.cache.fetch("api_geo_communes_by_pc_#{postal_code}", expires_in: 1.week, version: 3) do
+        communes_by_postal_code_map.fetch(postal_code, [])
+          .filter { !_1[:code].in?(['75056', '13055', '69123']) }
+          .sort_by { I18n.transliterate([_1[:name], _1[:postal_code]].join(' ')) }
+      end
     end
 
     def commune_name(departement_code, code)