diff --git a/nixos/modules/system/boot/systemd-unit-options.nix b/nixos/modules/system/boot/systemd-unit-options.nix
index c1f2c98afcd..bee21f1a8f3 100644
--- a/nixos/modules/system/boot/systemd-unit-options.nix
+++ b/nixos/modules/system/boot/systemd-unit-options.nix
@@ -24,7 +24,7 @@ in rec {
       in
         if isList (head defs'')
         then concatLists defs''
-        else mergeOneOption loc defs';
+        else mergeEqualOption loc defs';
   };
 
   sharedOptions = {