diff --git a/nixos/modules/misc/locate.nix b/nixos/modules/misc/locate.nix
index 654cce95ab2..0fe91435ce8 100644
--- a/nixos/modules/misc/locate.nix
+++ b/nixos/modules/misc/locate.nix
@@ -133,7 +133,7 @@ in {
           ''
             mkdir -m 0755 -p ${dirOf cfg.output}
             exec ${cfg.locate}/bin/updatedb \
-              ${optionalString (cfg.localuser != null) ''--localuser=${cfg.localuser}''} \
+              ${optionalString (cfg.localuser != null && ! isMLocate) ''--localuser=${cfg.localuser}''} \
               --output=${toString cfg.output} ${concatStringsSep " " cfg.extraFlags}
           '';
         environment = {