diff --git a/nixos/modules/services/monitoring/prometheus/exporters/mail.nix b/nixos/modules/services/monitoring/prometheus/exporters/mail.nix
index 7dc40293d464..61ca738fdd31 100644
--- a/nixos/modules/services/monitoring/prometheus/exporters/mail.nix
+++ b/nixos/modules/services/monitoring/prometheus/exporters/mail.nix
@@ -15,6 +15,7 @@ let
     nameValuePair
     toLower
     filterAttrs
+    removeAttrs
     escapeShellArg
     literalExpression
     mkIf
@@ -41,7 +42,7 @@ let
           )
         else
           nameValuePair (toLower name) value
-      ) (filterAttrs (n: _: !(n == "_module")) cfg.configuration)
+      ) (removeAttrs cfg.configuration [ "_module" ])
     )
   );