diff --git a/dune-project b/dune-project
index 02a19c226..b9511826f 100644
--- a/dune-project
+++ b/dune-project
@@ -74,5 +74,6 @@
   digestif
   xmlm
   (hc (>= 0.3))
+  (processor (>= 0.1))
   dune-site)
  (sites (share pyc) (share binc) (share libc)))
diff --git a/owi.opam b/owi.opam
index f22c66c10..793df28a4 100644
--- a/owi.opam
+++ b/owi.opam
@@ -42,6 +42,7 @@ depends: [
   "digestif"
   "xmlm"
   "hc" {>= "0.3"}
+  "processor" {>= "0.1"}
   "dune-site"
 ]
 build: [
diff --git a/src/bin/owi.ml b/src/bin/owi.ml
index cca620dc4..a5f0ae09b 100644
--- a/src/bin/owi.ml
+++ b/src/bin/owi.ml
@@ -60,12 +60,12 @@ let unsafe =
 
 let workers =
   let doc =
-    "number of workers for symbolic execution. Defaults to a machine-specific \
-     value given by the OCaml Domain.recommended_domain_count function."
+    "number of workers for symbolic execution. Defaults to the number of \
+     physical cores."
   in
   Cmdliner.Arg.(
     value
-    & opt int (Domain.recommended_domain_count ())
+    & opt int Processor.Query.core_count
     & info [ "workers"; "w" ] ~doc ~absent:"n" )
 
 let workspace =
diff --git a/src/dune b/src/dune
index 16ea55f62..3eb496277 100644
--- a/src/dune
+++ b/src/dune
@@ -98,6 +98,7 @@
   menhirLib
   ocaml_intrinsics
   ppxlib
+  processor
   sedlex
   uutf
   runtime_events