diff --git a/nixos/modules/services/mail/dovecot.nix b/nixos/modules/services/mail/dovecot.nix
index 950ac5859b62..b4cf0c4a2fc5 100644
--- a/nixos/modules/services/mail/dovecot.nix
+++ b/nixos/modules/services/mail/dovecot.nix
@@ -90,8 +90,6 @@ let
     }) cfg.sieve.pipeBins
   );
 
-  yesOrNo = v: if v then "yes" else "no";
-
   toOption =
     i: n: v:
     "${i}${toString n} = ${v}";
@@ -103,7 +101,7 @@ let
     if isInt v then
       toString v
     else if isBool v then
-      yesOrNo v
+      lib.boolToYesNo v
     else if isString v then
       v
     else if isPath v || isDerivation v then