diff --git a/lib/caqti_common_priv.ml b/lib/caqti_common_priv.ml
index c415053b..22ca8090 100644
--- a/lib/caqti_common_priv.ml
+++ b/lib/caqti_common_priv.ml
@@ -48,6 +48,12 @@ module List = struct
   let rec iter_r f = function
    | [] -> Ok ()
    | x :: xs -> (match f x with Ok () -> iter_r f xs | Error _ as r -> r)
+
+  let rec equal f xs ys =
+    (match xs, ys with
+     | [], [] -> true
+     | x :: xs', y :: ys' -> f x y && equal f xs' ys'
+     | [], _ :: _ | _ :: _, [] -> false)
 end
 
 let finally cleanup thunk =
diff --git a/lib/caqti_common_priv.mli b/lib/caqti_common_priv.mli
index 0007181e..cab4da1b 100644
--- a/lib/caqti_common_priv.mli
+++ b/lib/caqti_common_priv.mli
@@ -42,6 +42,7 @@ module List : sig
   val fold : ('a -> 'b -> 'b) -> 'a list -> 'b -> 'b
   val fold_r : ('a -> 'b -> ('b, 'e) result) -> 'a list -> 'b -> ('b, 'e) result
   val iter_r : ('a -> (unit, 'e) result) -> 'a list -> (unit, 'e) result
+  val equal : ('a -> 'b -> bool) -> 'a list -> 'b list -> bool
 end
 
 val finally : (unit -> unit) -> (unit -> 'a) -> 'a
diff --git a/lib/caqti_query.ml b/lib/caqti_query.ml
index b3db9308..fe951d61 100644
--- a/lib/caqti_query.ml
+++ b/lib/caqti_query.ml
@@ -14,6 +14,8 @@
  * along with this library.  If not, see <http://www.gnu.org/licenses/>.
  *)
 
+open Caqti_common_priv
+
 type t =
   | L of string
   | Q of string
@@ -45,13 +47,7 @@ let rec equal t1 t2 =
   | L s1, L s2 -> String.equal s1 s2
   | Q s1, Q s2 -> String.equal s1 s2
   | P i1, P i2 -> Int.equal i1 i2
-  | S l1, S l2 -> 
-    let rec list_equal a b =
-      match (a, b) with
-      | ([], []) -> true
-      | (a::x, b::y) -> equal a b && (list_equal x y)
-      | _ -> false in
-    list_equal l1 l2
+  | S ts1, S ts2 -> List.equal equal ts1 ts2
   | L _, _ -> false
   | Q _, _ -> false
   | P _, _ -> false