diff --git a/src/kernel_services/ast_queries/file.ml b/src/kernel_services/ast_queries/file.ml
index 3050fa18cbd5f99fa2e0249a6b92f721e0892486..5e9e16b366365422344d440fab01c2a5266a11f5 100644
--- a/src/kernel_services/ast_queries/file.ml
+++ b/src/kernel_services/ast_queries/file.ml
@@ -310,7 +310,7 @@ let () = Cmdline.run_after_exiting_stage machdep_help
 let set_machdep () =
   let m = Kernel.Machdep.get () in
   if not (mem_machdep m) then
-    Kernel.abort "@[unsupported machine %s.@ Try one of%t.@]" m pretty_machdeps
+    Kernel.abort "@[unsupported machine '%s'.@ Either use a predefined name among %t,@ or an YAML machdep file.@]" m pretty_machdeps
 
 let () = Cmdline.run_after_configuring_stage set_machdep