diff --git a/src/macros.rs b/src/macros.rs
index b4bb1ba5..8605a6c8 100644
--- a/src/macros.rs
+++ b/src/macros.rs
@@ -373,7 +373,7 @@ macro_rules! simple_enum {
                                             let v = vec![
                                                 $(stringify!($v),)+
                                             ];
-                                            format!("valid:{}",
+                                            format!("valid values:{}",
                                                 v.iter().fold(String::new(), |a, i| {
                                                     a + &format!(" {}", i)[..]
                                                 }))