diff --git a/nixos/modules/services/misc/redmine.nix b/nixos/modules/services/misc/redmine.nix
index 4cd2f35113ec..c53157fafd2a 100644
--- a/nixos/modules/services/misc/redmine.nix
+++ b/nixos/modules/services/misc/redmine.nix
@@ -442,6 +442,7 @@ in
         MemoryDenyWriteExecute = true;
         NoNewPrivileges = true;
         PrivateDevices = true;
+        PrivateMounts = true;
         PrivateTmp = true;
         ProcSubset = "pid";
         ProtectClock = true;