diff --git a/krebs/4lib/default.nix b/krebs/4lib/default.nix
index da936fad6..09d416d44 100644
--- a/krebs/4lib/default.nix
+++ b/krebs/4lib/default.nix
@@ -37,6 +37,11 @@ let out = rec {
   shell = import ./shell.nix { inherit lib; };
   tree = import ./tree.nix { inherit lib; };
 
+  lpad = n: c: s:
+    if stringLength s < n
+      then lpad n c (c + s)
+      else s;
+
   toC = x: let
     type = typeOf x;
     reject = throw "cannot convert ${type}";