diff --git a/tests/test_generics.rs b/tests/test_generics.rs
index 36f1181..bcbfee0 100644
--- a/tests/test_generics.rs
+++ b/tests/test_generics.rs
@@ -1,6 +1,7 @@
 #![allow(clippy::needless_late_init, clippy::uninlined_format_args)]
 
 use core::fmt::{self, Debug, Display};
+use core::str::FromStr;
 use thiserror::Error;
 
 pub struct NoFormat;
@@ -160,6 +161,24 @@ pub struct StructFromGeneric<E> {
 #[error(transparent)]
 pub struct StructTransparentGeneric<E>(pub E);
 
+// Should expand to:
+//
+//     impl<T: FromStr> Display for AssociatedTypeError<T>
+//     where
+//         T::Err: Display;
+//
+//     impl<T: FromStr> Error for AssociatedTypeError<T>
+//     where
+//         Self: Debug + Display;
+//
+#[derive(Error, Debug)]
+pub enum AssociatedTypeError<T: FromStr> {
+    #[error("couldn't parse matrix")]
+    Other,
+    #[error("couldn't parse entry: {0}")]
+    EntryParseError(T::Err),
+}
+
 // Regression test for https://github.com/dtolnay/thiserror/issues/345
 #[test]
 fn test_no_bound_on_named_fmt() {