diff --git a/1/basic.nix b/1/basic.nix
index 477b4f9..4e19a94 100644
--- a/1/basic.nix
+++ b/1/basic.nix
@@ -11,5 +11,5 @@ pipe input [
     (map toInt)
     sum
   ]))
-  (foldl' max 0)
+  (foldl1 max)
 ]
diff --git a/3/advanced.nix b/3/advanced.nix
index 85b498a..3ea47ef 100644
--- a/3/advanced.nix
+++ b/3/advanced.nix
@@ -15,7 +15,7 @@ pipe input [
   (groupwise 3)
   (map (flip pipe [
     (map strings.stringToCharacters)
-    (l: foldl' intersectLists (head l) l)
+    (foldl1 intersectLists)
     head
     prio
   ]))
diff --git a/lib/default.nix b/lib/default.nix
index 6fe3cb6..9766ecf 100644
--- a/lib/default.nix
+++ b/lib/default.nix
@@ -1,7 +1,9 @@
 let
   nixpkgsLib = import <nixpkgs/lib>;
 
-  aocLib = with nixpkgsLib; rec {
+  aocLib = self: with self; nixpkgsLib // {
+    foldl1 = f: xs: foldl' f (head xs) (tail xs);
+
     groupwise = size: l: let
       rest = drop size l;
     in [ (take size l) ] ++ optionals (rest != []) (groupwise size rest);
@@ -11,8 +13,8 @@ let
       (filter isString)
     ];
 
-    sum = foldl' add 0;
+    sum = foldl1 add;
 
     unpackAttrsCall = f: attrs: f attrs.a attrs.b;
   };
-in nixpkgsLib // aocLib
+in nixpkgsLib.fix aocLib