diff --git a/src/extra.rs b/src/extra.rs
index f18603d..b61e80a 100644
--- a/src/extra.rs
+++ b/src/extra.rs
@@ -26,6 +26,8 @@
 //! #### Example
 //!
 //! ```no_run
+//! #![cfg(feature = "validator")]
+//!
 //! use axum::extract::FromRequestParts;
 //! use axum::http::request::Parts;
 //! use axum::response::{IntoResponse, Response};
@@ -85,6 +87,8 @@
 //! #### Example
 //!
 //! ```no_run
+//! #![cfg(feature = "validator")]
+//!
 //! use axum::extract::FromRequestParts;
 //! use axum::http::request::Parts;
 //! use axum::http::StatusCode;
@@ -151,6 +155,8 @@
 //! #### Example
 //!
 //! ```no_run
+//! #![cfg(feature = "validator")]
+//!
 //! use axum::extract::FromRequestParts;
 //! use axum::http::request::Parts;
 //! use axum::response::{IntoResponse, Response};
diff --git a/src/extra/form.rs b/src/extra/form.rs
index 7787c33..9e8b1f8 100644
--- a/src/extra/form.rs
+++ b/src/extra/form.rs
@@ -65,8 +65,9 @@ mod tests {
     use crate::tests::{ValidTest, ValidTestParameter};
     use axum_extra::extract::Form;
     use reqwest::{RequestBuilder, StatusCode};
+    use serde::Serialize;
 
-    impl<T: ValidTestParameter> ValidTest for Form<T> {
+    impl<T: ValidTestParameter + Serialize> ValidTest for Form<T> {
         const ERROR_STATUS_CODE: StatusCode = StatusCode::BAD_REQUEST;
 
         fn set_valid_request(builder: RequestBuilder) -> RequestBuilder {
diff --git a/src/extra/query.rs b/src/extra/query.rs
index e233af0..2e7181d 100644
--- a/src/extra/query.rs
+++ b/src/extra/query.rs
@@ -69,8 +69,9 @@ mod tests {
     use axum::http::StatusCode;
     use axum_extra::extract::Query;
     use reqwest::RequestBuilder;
+    use serde::Serialize;
 
-    impl<T: ValidTestParameter> ValidTest for Query<T> {
+    impl<T: ValidTestParameter + Serialize> ValidTest for Query<T> {
         const ERROR_STATUS_CODE: StatusCode = StatusCode::BAD_REQUEST;
 
         fn set_valid_request(builder: RequestBuilder) -> RequestBuilder {
diff --git a/src/form.rs b/src/form.rs
index d3e52f0..8cc3711 100644
--- a/src/form.rs
+++ b/src/form.rs
@@ -12,6 +12,8 @@
 //! ## Example
 //!
 //! ```no_run
+//! #![cfg(feature = "validator")]
+//!
 //! use axum::routing::post;
 //! use axum::Form;
 //! use axum::Router;
@@ -66,8 +68,9 @@ mod tests {
     use axum::http::StatusCode;
     use axum::Form;
     use reqwest::RequestBuilder;
+    use serde::Serialize;
 
-    impl<T: ValidTestParameter> ValidTest for Form<T> {
+    impl<T: ValidTestParameter + Serialize> ValidTest for Form<T> {
         const ERROR_STATUS_CODE: StatusCode = StatusCode::UNPROCESSABLE_ENTITY;
 
         fn set_valid_request(builder: RequestBuilder) -> RequestBuilder {
diff --git a/src/json.rs b/src/json.rs
index 83dcb4f..1e674b5 100644
--- a/src/json.rs
+++ b/src/json.rs
@@ -12,6 +12,7 @@
 //! ## Example
 //!
 //! ```no_run
+//! #![cfg(feature = "validator")]
 //!
 //! use axum::routing::post;
 //! use axum::Json;
@@ -67,8 +68,9 @@ mod tests {
     use axum::http::StatusCode;
     use axum::Json;
     use reqwest::RequestBuilder;
+    use serde::Serialize;
 
-    impl<T: ValidTestParameter> ValidTest for Json<T> {
+    impl<T: ValidTestParameter + Serialize> ValidTest for Json<T> {
         const ERROR_STATUS_CODE: StatusCode = StatusCode::UNPROCESSABLE_ENTITY;
 
         fn set_valid_request(builder: RequestBuilder) -> RequestBuilder {
diff --git a/src/lib.rs b/src/lib.rs
index 62b426c..28d5fbb 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -55,10 +55,9 @@ pub use crate::garde::{Garde, GardeRejection};
 #[cfg(test)]
 mod tests {
     use reqwest::{RequestBuilder, StatusCode};
-    use serde::Serialize;
 
     /// # Valid test parameter
-    pub trait ValidTestParameter: Serialize + 'static {
+    pub trait ValidTestParameter: 'static {
         /// Create a valid parameter
         fn valid() -> &'static Self;
         /// Create an error serializable array
diff --git a/src/msgpack.rs b/src/msgpack.rs
index 2feb911..8c6a065 100644
--- a/src/msgpack.rs
+++ b/src/msgpack.rs
@@ -12,6 +12,7 @@
 //! ## Example
 //!
 //! ```no_run
+//!#![cfg(feature = "validator")]
 //!
 //! use axum::routing::post;
 //! use axum::Router;
@@ -91,8 +92,9 @@ mod tests {
     use axum::http::StatusCode;
     use axum_msgpack::{MsgPack, MsgPackRaw};
     use reqwest::RequestBuilder;
+    use serde::Serialize;
 
-    impl<T: ValidTestParameter> ValidTest for MsgPack<T> {
+    impl<T: ValidTestParameter + Serialize> ValidTest for MsgPack<T> {
         const ERROR_STATUS_CODE: StatusCode = StatusCode::BAD_REQUEST;
 
         fn set_valid_request(builder: RequestBuilder) -> RequestBuilder {
@@ -119,7 +121,7 @@ mod tests {
         }
     }
 
-    impl<T: ValidTestParameter> ValidTest for MsgPackRaw<T> {
+    impl<T: ValidTestParameter + Serialize> ValidTest for MsgPackRaw<T> {
         const ERROR_STATUS_CODE: StatusCode = StatusCode::BAD_REQUEST;
 
         fn set_valid_request(builder: RequestBuilder) -> RequestBuilder {
diff --git a/src/path.rs b/src/path.rs
index 75a7fa0..6e86619 100644
--- a/src/path.rs
+++ b/src/path.rs
@@ -8,6 +8,7 @@
 //! ## Example
 //!
 //! ```no_run
+//! #![cfg(feature = "validator")]
 //!
 //! use axum::extract::Path;
 //! use axum::routing::post;
diff --git a/src/query.rs b/src/query.rs
index 80c9318..1556a7d 100644
--- a/src/query.rs
+++ b/src/query.rs
@@ -12,6 +12,7 @@
 //! ## Example
 //!
 //! ```no_run
+//! #![cfg(feature = "validator")]
 //!
 //! use axum::extract::Query;
 //! use axum::routing::post;
@@ -70,8 +71,9 @@ mod tests {
     use axum::extract::Query;
     use axum::http::StatusCode;
     use reqwest::RequestBuilder;
+    use serde::Serialize;
 
-    impl<T: ValidTestParameter> ValidTest for Query<T> {
+    impl<T: ValidTestParameter + Serialize> ValidTest for Query<T> {
         const ERROR_STATUS_CODE: StatusCode = StatusCode::BAD_REQUEST;
 
         fn set_valid_request(builder: RequestBuilder) -> RequestBuilder {
diff --git a/src/typed_header.rs b/src/typed_header.rs
index a20dcb9..8a71193 100644
--- a/src/typed_header.rs
+++ b/src/typed_header.rs
@@ -12,6 +12,8 @@
 //! ## Example
 //!
 //! ```no_run
+//! #![cfg(feature = "validator")]
+//!
 //! use axum::headers::{Error, Header, HeaderValue};
 //! use axum::http::HeaderName;
 //! use axum::routing::post;
diff --git a/src/typed_multipart.rs b/src/typed_multipart.rs
index e733e7b..08bfc62 100644
--- a/src/typed_multipart.rs
+++ b/src/typed_multipart.rs
@@ -12,6 +12,8 @@
 //! ## Example
 //!
 //! ```no_run
+//! #![cfg(feature = "validator")]
+//!
 //! use axum::routing::post;
 //! use axum::Router;
 //! use axum_typed_multipart::{BaseMultipart, TryFromMultipart, TypedMultipart, TypedMultipartError};
diff --git a/src/yaml.rs b/src/yaml.rs
index dea49ed..dfa4eb5 100644
--- a/src/yaml.rs
+++ b/src/yaml.rs
@@ -8,11 +8,12 @@
 //!
 //! 1. Implement `Deserialize` and `Validate` for your data type `T`.
 //! 2. In your handler function, use `Valid<Yaml<T>>` as some parameter's type.
-
 //!
 //! ## Example
 //!
 //! ```no_run
+//! #![cfg(feature = "validator")]
+//!
 //! use axum::routing::post;
 //! use axum::Router;
 //! use axum_valid::Valid;
@@ -70,8 +71,9 @@ mod tests {
     use axum::http::StatusCode;
     use axum_yaml::Yaml;
     use reqwest::RequestBuilder;
+    use serde::Serialize;
 
-    impl<T: ValidTestParameter> ValidTest for Yaml<T> {
+    impl<T: ValidTestParameter + Serialize> ValidTest for Yaml<T> {
         const ERROR_STATUS_CODE: StatusCode = StatusCode::UNSUPPORTED_MEDIA_TYPE;
 
         fn set_valid_request(builder: RequestBuilder) -> RequestBuilder {