diff --git a/src/blocking_IO.ml b/src/blocking_IO.ml
index 845d46aa..81a04132 100644
--- a/src/blocking_IO.ml
+++ b/src/blocking_IO.ml
@@ -14,7 +14,7 @@ let fail = raise
 let stdin = stdin
 let stdout = stdout
 
-let spawn f =
+let default_spawn_ f =
   let run () =
     try f()
     with e ->
@@ -22,9 +22,14 @@ let spawn f =
         "uncaught exception in `spawn`:\n%s\n%!"
         (Printexc.to_string e));
       raise e
-in
+  in
   ignore (Thread.create run () : Thread.t)
 
+let spawn_ref_ = ref default_spawn_
+
+let set_spawn_function f = spawn_ref_ := f
+let spawn f = !spawn_ref_ f
+
 let catch f g =
   try f()
   with e -> g e
diff --git a/src/blocking_IO.mli b/src/blocking_IO.mli
index 0ffde6ef..bdec4dbe 100644
--- a/src/blocking_IO.mli
+++ b/src/blocking_IO.mli
@@ -4,3 +4,7 @@
 include Sigs.IO with type 'a t = 'a
      and type in_channel = in_channel
      and type out_channel = out_channel
+
+val set_spawn_function : ((unit -> unit) -> unit) -> unit
+(** Change the way the LSP server spawns new threads to handle
+    client queries. For example, one might use a thread pool. *)