diff --git a/pkgs/top-level/all-packages.nix b/pkgs/top-level/all-packages.nix
index 216cb019f011..eb9eca8ba719 100644
--- a/pkgs/top-level/all-packages.nix
+++ b/pkgs/top-level/all-packages.nix
@@ -25581,7 +25581,11 @@ with pkgs;
 
   mackerel-agent = callPackage ../servers/monitoring/mackerel-agent { };
 
-  mailmanPackages = callPackage ../servers/mail/mailman { };
+  mailmanPackages = callPackage ../servers/mail/mailman {
+    # Hyperkitty test fails with 3.12:
+    # https://gitlab.com/mailman/hyperkitty/-/issues/514
+    python3 = python311;
+  };
   inherit (mailmanPackages) mailman mailman-hyperkitty;
   mailman-web = mailmanPackages.web;