diff --git a/src/discover/discover.ml b/src/discover/discover.ml
index ce892e8..66c5565 100644
--- a/src/discover/discover.ml
+++ b/src/discover/discover.ml
@@ -14,11 +14,15 @@ let () =
   main
     ~name:"discover"
     ~args:[ "-o", Set_string output, "FILENAME output file" ]
-    (fun _c ->
+    (fun c ->
       let f,oc = Filename.open_temp_file "baseconf" ".c" in
       let has_popcnt =
-        Fun.protect ~finally:(fun () -> close_out oc; Sys.remove f)
-          (fun () -> Out_channel.(output_string oc program; flush oc);
-            Sys.command (Printf.sprintf "cc %s -mpopcnt -o /dev/null >/dev/null 2>&1" f) = 0) in
+        match ocaml_config_var_exn c "system" with
+        | "macosx" -> false
+        | _ ->
+          Fun.protect ~finally:(fun () -> close_out oc; Sys.remove f)
+            (fun () -> Out_channel.(output_string oc program; flush oc);
+              Sys.command (Printf.sprintf "cc %s -mpopcnt -o /dev/null >/dev/null 2>&1" f) = 0)
+      in
       Flags.write_sexp !output (if has_popcnt then [ "-mpopcnt" ] else []))
 ;;