diff --git a/src/baselib/ocsigen_lib_base.ml b/src/baselib/ocsigen_lib_base.ml
index a02796328..0969197cb 100644
--- a/src/baselib/ocsigen_lib_base.ml
+++ b/src/baselib/ocsigen_lib_base.ml
@@ -173,6 +173,13 @@ module List = struct
       | [] -> []
       | x :: xs -> chop (n-1) xs
 
+  let rec split_at n xs =
+    if n <= 0
+    then [], xs
+    else match xs with
+           | [] -> [], []
+           | x::xs -> let l,r = split_at (n-1) xs in x::l, r
+
 end
 
 (*****************************************************************************)
diff --git a/src/baselib/ocsigen_lib_base.mli b/src/baselib/ocsigen_lib_base.mli
index bca337a76..3891feb2c 100644
--- a/src/baselib/ocsigen_lib_base.mli
+++ b/src/baselib/ocsigen_lib_base.mli
@@ -91,6 +91,7 @@ module List : sig
   val is_prefix : 'a list -> 'a list -> bool
 
   val chop : int -> 'a list -> 'a list
+  val split_at : int -> 'a list -> 'a list * 'a list
 
 end