diff --git a/pkgs/lib/attrsets.nix b/pkgs/lib/attrsets.nix
index f39b46db6213..fcaf4f5c9b5c 100644
--- a/pkgs/lib/attrsets.nix
+++ b/pkgs/lib/attrsets.nix
@@ -273,6 +273,6 @@ rec {
   # override only the attributes that are already present in the old set
   # useful for deep-overriding
   overrideExisting = old: new:
-  old // listToAttrs (map (attr: nameValuePair attr (attrByPath [attr] (getAttr attr old) new)) (attrNames old));
+    old // listToAttrs (map (attr: nameValuePair attr (attrByPath [attr] (getAttr attr old) new)) (attrNames old));
 
 }