diff --git a/nixos/modules/services/web-servers/nginx/default.nix b/nixos/modules/services/web-servers/nginx/default.nix
index 85c76ed59d66..09e7c5c894ae 100644
--- a/nixos/modules/services/web-servers/nginx/default.nix
+++ b/nixos/modules/services/web-servers/nginx/default.nix
@@ -480,7 +480,7 @@ in
         defaultText = literalExpression "pkgs.nginxStable";
         type = types.package;
         apply = p: p.override {
-          modules = p.modules ++ cfg.additionalModules;
+          modules = lib.unique (p.modules ++ cfg.additionalModules);
         };
         description = lib.mdDoc ''
           Nginx package to use. This defaults to the stable version. Note