diff --git a/Cargo.toml b/Cargo.toml
index d7f9b78..82c2e83 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -1,6 +1,6 @@
 [package]
 name = "axum-valid"
-version = "0.4.1"
+version = "0.4.2"
 description = "Validation tools for axum using the validator library."
 authors = ["GengTeng <me@gteng.org>"]
 license = "MIT"
@@ -23,11 +23,6 @@ edition = "2021"
 axum = { version = "0.6.18", default-features = false }
 validator = "0.16.0"
 
-[dependencies.serde_json]
-package = "serde_json"
-version = "1.0.103"
-optional = true
-
 [dev-dependencies]
 anyhow = "1.0.71"
 axum = { version = "0.6.18" }
@@ -37,11 +32,12 @@ reqwest = { version = "0.11.18", features = ["json"] }
 serde = { version = "1.0.163", features = ["derive"] }
 validator = { version = "0.16.0", features = ["derive"] }
 serde_json = "1.0.103"
+mime = "0.3.17"
 
 [features]
 default = ["json", "form", "query"]
 json = ["axum/json"]
 form = ["axum/form"]
 query = ["axum/query"]
-into_json = ["serde_json"]
+into_json = ["json"]
 422 = []
diff --git a/src/lib.rs b/src/lib.rs
index f273af8..cce4e61 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -47,16 +47,14 @@ impl<E: IntoResponse> IntoResponse for ValidRejection<E> {
         match self {
             ValidRejection::Valid(validate_error) => {
                 #[cfg(feature = "into_json")]
-                match serde_json::to_string(&validate_error) {
-                    Ok(json) => (VALIDATION_ERROR_STATUS, json),
-                    Err(error) => (
-                        StatusCode::INTERNAL_SERVER_ERROR,
-                        format!("Failed to serialize validation error into JSON ({validate_error}): {error}"),
-                    ),
+                {
+                    (VALIDATION_ERROR_STATUS, axum::Json(validate_error)).into_response()
                 }
                 #[cfg(not(feature = "into_json"))]
-                (VALIDATION_ERROR_STATUS, validate_error.to_string())
-            }.into_response(),
+                {
+                    (VALIDATION_ERROR_STATUS, validate_error.to_string()).into_response()
+                }
+            }
             ValidRejection::Inner(json_error) => json_error.into_response(),
         }
     }
diff --git a/tests/basic.rs b/tests/basic.rs
index b967b53..72a5469 100644
--- a/tests/basic.rs
+++ b/tests/basic.rs
@@ -15,6 +15,8 @@ use serde_json::json;
 use std::net::SocketAddr;
 use validator::Validate;
 
+mod utils;
+
 mod route {
     pub const PATH: &str = "/path/:v0/:v1";
     pub const QUERY: &str = "/query";
@@ -78,10 +80,7 @@ async fn main() -> anyhow::Result<()> {
         .await?;
     assert_eq!(invalid_path_response.status(), VALIDATION_ERROR_STATUS);
     #[cfg(feature = "into_json")]
-    assert!(invalid_path_response
-        .json::<serde_json::Value>()
-        .await
-        .is_ok());
+    utils::check_json(invalid_path_response).await;
     println!("Valid<Path<...>> works.");
 
     // Valid<Query<...>>
@@ -107,10 +106,7 @@ async fn main() -> anyhow::Result<()> {
         .await?;
     assert_eq!(invalid_query_response.status(), VALIDATION_ERROR_STATUS);
     #[cfg(feature = "into_json")]
-    assert!(invalid_query_response
-        .json::<serde_json::Value>()
-        .await
-        .is_ok());
+    utils::check_json(invalid_query_response).await;
     println!("Valid<Query<...>> works.");
 
     // Valid<Form<...>>
@@ -139,10 +135,7 @@ async fn main() -> anyhow::Result<()> {
         .await?;
     assert_eq!(invalid_form_response.status(), VALIDATION_ERROR_STATUS);
     #[cfg(feature = "into_json")]
-    assert!(invalid_form_response
-        .json::<serde_json::Value>()
-        .await
-        .is_ok());
+    utils::check_json(invalid_form_response).await;
     println!("Valid<Form<...>> works.");
 
     // Valid<Json<...>>
@@ -171,10 +164,7 @@ async fn main() -> anyhow::Result<()> {
         .await?;
     assert_eq!(invalid_json_response.status(), VALIDATION_ERROR_STATUS);
     #[cfg(feature = "into_json")]
-    assert!(invalid_json_response
-        .json::<serde_json::Value>()
-        .await
-        .is_ok());
+    utils::check_json(invalid_json_response).await;
     println!("Valid<Json<...>> works.");
 
     drop(server_guard);
diff --git a/tests/custom.rs b/tests/custom.rs
index bd6ecdd..f3eca8b 100644
--- a/tests/custom.rs
+++ b/tests/custom.rs
@@ -12,6 +12,8 @@ use serde::{Deserialize, Serialize};
 use std::net::SocketAddr;
 use validator::Validate;
 
+mod utils;
+
 const MY_DATA_HEADER: &str = "My-Data";
 
 // 1. Implement your own extractor.
@@ -124,10 +126,7 @@ async fn main() -> anyhow::Result<()> {
         .await?;
     assert_eq!(invalid_my_data_response.status(), VALIDATION_ERROR_STATUS);
     #[cfg(feature = "into_json")]
-    assert!(invalid_my_data_response
-        .json::<serde_json::Value>()
-        .await
-        .is_ok());
+    utils::check_json(invalid_my_data_response).await;
     println!("Valid<MyData> works.");
 
     drop(server_guard);
diff --git a/tests/utils.rs b/tests/utils.rs
new file mode 100644
index 0000000..66cc557
--- /dev/null
+++ b/tests/utils.rs
@@ -0,0 +1,9 @@
+/// Check if the response is a json response
+#[cfg(feature = "into_json")]
+pub async fn check_json(response: reqwest::Response) {
+    assert_eq!(
+        response.headers()[axum::http::header::CONTENT_TYPE],
+        axum::http::HeaderValue::from_static(mime::APPLICATION_JSON.as_ref())
+    );
+    assert!(response.json::<serde_json::Value>().await.is_ok());
+}