diff --git a/CHANGELOG.md b/CHANGELOG.md
index 3b3e6d2e..565a4eac 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -5,7 +5,7 @@
 ### Changed
 
 - Change `get_or_try_insert_with` to return a concrete error type rather
-  than a trait object. ([#23][gh-pull-0023])
+  than a trait object. ([#23][gh-pull-0023], [#37][gh-pull-0037])
 
 
 ## Version 0.5.2
@@ -112,6 +112,7 @@
 
 [caffeine-git]: https://github.com/ben-manes/caffeine
 
+[gh-pull-0037]: https://github.com/moka-rs/moka/pull/37/
 [gh-pull-0033]: https://github.com/moka-rs/moka/pull/33/
 [gh-issue-0031]: https://github.com/moka-rs/moka/issues/31/
 [gh-pull-0030]: https://github.com/moka-rs/moka/pull/30/
diff --git a/src/future/cache.rs b/src/future/cache.rs
index a35e82c7..5772a3d9 100644
--- a/src/future/cache.rs
+++ b/src/future/cache.rs
@@ -16,7 +16,6 @@ use std::{
     any::TypeId,
     borrow::Borrow,
     collections::hash_map::RandomState,
-    error::Error,
     future::Future,
     hash::{BuildHasher, Hash},
     sync::Arc,
@@ -439,7 +438,7 @@ where
     pub async fn get_or_try_insert_with<F, E>(&self, key: K, init: F) -> Result<V, Arc<E>>
     where
         F: Future<Output = Result<V, E>> + Send + 'static,
-        E: Error + Send + Sync + 'static,
+        E: Send + Sync + 'static,
     {
         let hash = self.base.hash(&key);
         let key = Arc::new(key);
@@ -632,7 +631,7 @@ where
     ) -> Result<V, Arc<E>>
     where
         F: Future<Output = Result<V, E>>,
-        E: Error + Send + Sync + 'static,
+        E: Send + Sync + 'static,
     {
         if let Some(v) = self.base.get_with_hash(&key, hash) {
             return Ok(v);
@@ -1166,8 +1165,9 @@ mod tests {
     async fn get_or_try_insert_with() {
         use std::sync::Arc;
 
-        #[derive(thiserror::Error, Debug)]
-        #[error("{}", _0)]
+        // Note that MyError does not implement std::error::Error trait
+        // like anyhow::Error.
+        #[derive(Debug)]
         pub struct MyError(String);
 
         type MyResult<T> = Result<T, Arc<MyError>>;
diff --git a/src/future/value_initializer.rs b/src/future/value_initializer.rs
index 419a7004..9a67f520 100644
--- a/src/future/value_initializer.rs
+++ b/src/future/value_initializer.rs
@@ -1,7 +1,6 @@
 use async_lock::RwLock;
 use std::{
     any::{Any, TypeId},
-    error::Error,
     future::Future,
     hash::{BuildHasher, Hash},
     sync::Arc,
@@ -68,7 +67,7 @@ where
     pub(crate) async fn try_init_or_read<F, E>(&self, key: Arc<K>, init: F) -> InitResult<V, E>
     where
         F: Future<Output = Result<V, E>>,
-        E: Error + Send + Sync + 'static,
+        E: Send + Sync + 'static,
     {
         use InitResult::*;
 
diff --git a/src/sync/cache.rs b/src/sync/cache.rs
index ee8a3f37..2ccabef4 100644
--- a/src/sync/cache.rs
+++ b/src/sync/cache.rs
@@ -11,7 +11,6 @@ use std::{
     any::TypeId,
     borrow::Borrow,
     collections::hash_map::RandomState,
-    error::Error,
     hash::{BuildHasher, Hash},
     sync::Arc,
     time::Duration,
@@ -423,7 +422,7 @@ where
     pub fn get_or_try_insert_with<F, E>(&self, key: K, init: F) -> Result<V, Arc<E>>
     where
         F: FnOnce() -> Result<V, E>,
-        E: Error + Send + Sync + 'static,
+        E: Send + Sync + 'static,
     {
         let hash = self.base.hash(&key);
         let key = Arc::new(key);
@@ -438,7 +437,7 @@ where
     ) -> Result<V, Arc<E>>
     where
         F: FnOnce() -> Result<V, E>,
-        E: Error + Send + Sync + 'static,
+        E: Send + Sync + 'static,
     {
         if let Some(v) = self.get_with_hash(&key, hash) {
             return Ok(v);
@@ -1009,8 +1008,9 @@ mod tests {
             thread::{sleep, spawn},
         };
 
-        #[derive(thiserror::Error, Debug)]
-        #[error("{}", _0)]
+        // Note that MyError does not implement std::error::Error trait
+        // like anyhow::Error.
+        #[derive(Debug)]
         pub struct MyError(String);
 
         type MyResult<T> = Result<T, Arc<MyError>>;
diff --git a/src/sync/value_initializer.rs b/src/sync/value_initializer.rs
index 1a2d312a..8b6aecc2 100644
--- a/src/sync/value_initializer.rs
+++ b/src/sync/value_initializer.rs
@@ -1,7 +1,6 @@
 use parking_lot::RwLock;
 use std::{
     any::{Any, TypeId},
-    error::Error,
     hash::{BuildHasher, Hash},
     sync::Arc,
 };
@@ -63,7 +62,7 @@ where
     pub(crate) fn try_init_or_read<F, E>(&self, key: Arc<K>, init: F) -> InitResult<V, E>
     where
         F: FnOnce() -> Result<V, E>,
-        E: Error + Send + Sync + 'static,
+        E: Send + Sync + 'static,
     {
         use InitResult::*;