1 files changed, 1 insertions, 1 deletions
diff --git a/process.c b/process.c
index 4f68d690fb..073b380f74 100644
--- a/process.c
+++ b/process.c
@@ -3262,7 +3262,7 @@ rb_f_sleep(int argc, VALUE *argv)
 	rb_thread_wait_for(rb_time_interval(argv[0]));
     }
     else {
-	rb_raise(rb_eArgError, "wrong number of arguments");
+	rb_raise(rb_eArgError, "wrong number of arguments (%d for 0..1)", argc);
     }
 
     end = time(0) - beg;