diff --git a/lib/strings.nix b/lib/strings.nix
index bb07f40d7a55..1eb6cf9c1afb 100644
--- a/lib/strings.nix
+++ b/lib/strings.nix
@@ -18,6 +18,7 @@ rec {
     elemAt
     filter
     fromJSON
+    genList
     head
     isInt
     isList
@@ -346,7 +347,7 @@ rec {
        => [ "�" "�" "�" "�" ]
   */
   stringToCharacters = s:
-    map (p: substring p 1 s) (lib.range 0 (stringLength s - 1));
+    genList (p: substring p 1 s) (stringLength s);
 
   /* Manipulate a string character by character and replace them by
      strings before concatenating the results.