diff --git a/src/d_pool_.ml b/src/d_pool_.ml
index 189a02cb..250f3fd7 100644
--- a/src/d_pool_.ml
+++ b/src/d_pool_.ml
@@ -14,7 +14,7 @@ let domains_ : worker array lazy_t =
   lazy
     ((* number of domains we spawn. Note that we spawn n-1 domains
         because there already is the main domain running. *)
-     let n = Domain_.recommended_number () - 1 in
+     let n = max 1 (Domain_.recommended_number () - 1) in
      Array.init n (fun i ->
          let q = Bb_queue.create () in
          let _domain : domain = Domain_.spawn (fun () -> work_ i q) in