diff --git a/hosts/ocaml/bin/sx_server.ml b/hosts/ocaml/bin/sx_server.ml
index c904fec..c6ba57e 100644
--- a/hosts/ocaml/bin/sx_server.ml
+++ b/hosts/ocaml/bin/sx_server.ml
@@ -633,7 +633,10 @@ let make_server_env () =
   bind "parse-int" (fun args ->
     match args with
     | [String s] -> (try Number (float_of_int (int_of_string s)) with _ -> Nil)
-    | [Number n] -> Number (Float.round n)
+    | [String s; default_val] ->
+      (try Number (float_of_int (int_of_string s)) with _ -> default_val)
+    | [Number n] | [Number n; _] -> Number (Float.round n)
+    | [_; default_val] -> default_val
     | _ -> Nil);
 
   bind "json-encode" (fun args -> io_request "helper" (String "json-encode" :: args));