diff --git a/Cargo.toml b/Cargo.toml
index 7844cb6..6899636 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -1,6 +1,6 @@
 [package]
 name = "openai-api-rs"
-version = "0.1.2"
+version = "0.1.3"
 edition = "2021"
 authors = ["Dongri Jin <dongrify@gmail.com>"]
 license = "MIT"
diff --git a/README.md b/README.md
index 3d3a2b6..cb899c1 100644
--- a/README.md
+++ b/README.md
@@ -4,7 +4,7 @@
 Cargo.toml
 ```toml
 [dependencies]
-openai-api-rs = "0.1.2"
+openai-api-rs = "0.1.3"
 ```
 
 ## Example:
diff --git a/src/v1/api.rs b/src/v1/api.rs
index 32a260e..c6a4deb 100644
--- a/src/v1/api.rs
+++ b/src/v1/api.rs
@@ -12,6 +12,7 @@ use crate::v1::image::{
     ImageVariationRequest, ImageVariationResponse,
 };
 use reqwest::Response;
+use std::io::Error;
 
 const APU_URL_V1: &str = "https://api.openai.com/v1";
 
@@ -28,7 +29,7 @@ impl Client {
         &self,
         path: &str,
         params: &T,
-    ) -> Result<Response, Box<dyn std::error::Error>> {
+    ) -> Result<Response, Error> {
         let client = reqwest::Client::new();
         let url = format!("{APU_URL_V1}{path}");
         let res = client
@@ -44,16 +45,16 @@ impl Client {
         match res {
             Ok(res) => match res.status().is_success() {
                 true => Ok(res),
-                false => Err(Box::new(std::io::Error::new(
+                false => Err(Error::new(
                     std::io::ErrorKind::Other,
                     format!("{}: {}", res.status(), res.text().await.unwrap()),
-                ))),
+                )),
             },
-            Err(e) => Err(Box::new(e)),
+            Err(e) => Err(self.new_error(e)),
         }
     }
 
-    pub async fn get(&self, path: &str) -> Result<Response, Box<dyn std::error::Error>> {
+    pub async fn get(&self, path: &str) -> Result<Response, Error> {
         let client = reqwest::Client::new();
         let url = format!("{APU_URL_V1}{path}");
         let res = client
@@ -68,16 +69,16 @@ impl Client {
         match res {
             Ok(res) => match res.status().is_success() {
                 true => Ok(res),
-                false => Err(Box::new(std::io::Error::new(
+                false => Err(Error::new(
                     std::io::ErrorKind::Other,
                     format!("{}: {}", res.status(), res.text().await.unwrap()),
-                ))),
+                )),
             },
-            Err(e) => Err(Box::new(e)),
+            Err(e) => Err(self.new_error(e)),
         }
     }
 
-    pub async fn delete(&self, path: &str) -> Result<Response, Box<dyn std::error::Error>> {
+    pub async fn delete(&self, path: &str) -> Result<Response, Error> {
         let client = reqwest::Client::new();
         let url = format!("{APU_URL_V1}{path}");
         let res = client
@@ -92,176 +93,143 @@ impl Client {
         match res {
             Ok(res) => match res.status().is_success() {
                 true => Ok(res),
-                false => Err(Box::new(std::io::Error::new(
+                false => Err(Error::new(
                     std::io::ErrorKind::Other,
                     format!("{}: {}", res.status(), res.text().await.unwrap()),
-                ))),
+                )),
             },
-            Err(e) => Err(Box::new(e)),
+            Err(e) => Err(self.new_error(e)),
         }
     }
 
-    pub async fn completion(
-        &self,
-        req: CompletionRequest,
-    ) -> Result<CompletionResponse, Box<dyn std::error::Error>> {
-        let res = self.post("/completions", &req).await;
-        match res {
-            Ok(res) => {
-                let r = res.json::<CompletionResponse>().await?;
-                Ok(r)
-            }
-            Err(e) => Err(e),
+    pub async fn completion(&self, req: CompletionRequest) -> Result<CompletionResponse, Error> {
+        let res = self.post("/completions", &req).await?;
+        let r = res.json::<CompletionResponse>().await;
+        match r {
+            Ok(r) => Ok(r),
+            Err(e) => Err(self.new_error(e)),
         }
     }
 
-    pub async fn edit(&self, req: EditRequest) -> Result<EditResponse, Box<dyn std::error::Error>> {
-        let res = self.post("/edits", &req).await;
-        match res {
-            Ok(res) => {
-                let r = res.json::<EditResponse>().await?;
-                Ok(r)
-            }
-            Err(e) => Err(e),
+    pub async fn edit(&self, req: EditRequest) -> Result<EditResponse, Error> {
+        let res = self.post("/edits", &req).await?;
+        let r = res.json::<EditResponse>().await;
+        match r {
+            Ok(r) => Ok(r),
+            Err(e) => Err(self.new_error(e)),
         }
     }
 
     pub async fn image_generation(
         &self,
         req: ImageGenerationRequest,
-    ) -> Result<ImageGenerationResponse, Box<dyn std::error::Error>> {
-        let res = self.post("/images/generations", &req).await;
-        match res {
-            Ok(res) => {
-                let r = res.json::<ImageGenerationResponse>().await?;
-                Ok(r)
-            }
-            Err(e) => Err(e),
+    ) -> Result<ImageGenerationResponse, Error> {
+        let res = self.post("/images/generations", &req).await?;
+        let r = res.json::<ImageGenerationResponse>().await;
+        match r {
+            Ok(r) => Ok(r),
+            Err(e) => Err(self.new_error(e)),
         }
     }
 
-    pub async fn image_edit(
-        &self,
-        req: ImageEditRequest,
-    ) -> Result<ImageEditResponse, Box<dyn std::error::Error>> {
-        let res = self.post("/images/edits", &req).await;
-        match res {
-            Ok(res) => {
-                let r = res.json::<ImageEditResponse>().await?;
-                Ok(r)
-            }
-            Err(e) => Err(e),
+    pub async fn image_edit(&self, req: ImageEditRequest) -> Result<ImageEditResponse, Error> {
+        let res = self.post("/images/edits", &req).await?;
+        let r = res.json::<ImageEditResponse>().await;
+        match r {
+            Ok(r) => Ok(r),
+            Err(e) => Err(self.new_error(e)),
         }
     }
 
     pub async fn image_variation(
         &self,
         req: ImageVariationRequest,
-    ) -> Result<ImageVariationResponse, Box<dyn std::error::Error>> {
-        let res = self.post("/images/variations", &req).await;
-        match res {
-            Ok(res) => {
-                let r = res.json::<ImageVariationResponse>().await?;
-                Ok(r)
-            }
-            Err(e) => Err(e),
+    ) -> Result<ImageVariationResponse, Error> {
+        let res = self.post("/images/variations", &req).await?;
+        let r = res.json::<ImageVariationResponse>().await;
+        match r {
+            Ok(r) => Ok(r),
+            Err(e) => Err(self.new_error(e)),
         }
     }
 
-    pub async fn embedding(
-        &self,
-        req: EmbeddingRequest,
-    ) -> Result<EmbeddingResponse, Box<dyn std::error::Error>> {
-        let res = self.post("/embeddings", &req).await;
-        match res {
-            Ok(res) => {
-                let r = res.json::<EmbeddingResponse>().await?;
-                Ok(r)
-            }
-            Err(e) => Err(e),
+    pub async fn embedding(&self, req: EmbeddingRequest) -> Result<EmbeddingResponse, Error> {
+        let res = self.post("/embeddings", &req).await?;
+        let r = res.json::<EmbeddingResponse>().await;
+        match r {
+            Ok(r) => Ok(r),
+            Err(e) => Err(self.new_error(e)),
         }
     }
 
-    pub async fn file_list(&self) -> Result<FileListResponse, Box<dyn std::error::Error>> {
-        let res = self.get("/files").await;
-        match res {
-            Ok(res) => {
-                let r = res.json::<FileListResponse>().await?;
-                Ok(r)
-            }
-            Err(e) => Err(e),
+    pub async fn file_list(&self) -> Result<FileListResponse, Error> {
+        let res = self.get("/files").await?;
+        let r = res.json::<FileListResponse>().await;
+        match r {
+            Ok(r) => Ok(r),
+            Err(e) => Err(self.new_error(e)),
         }
     }
 
-    pub async fn file_upload(
-        &self,
-        req: FileUploadRequest,
-    ) -> Result<FileUploadResponse, Box<dyn std::error::Error>> {
-        let res = self.post("/files", &req).await;
-        match res {
-            Ok(res) => {
-                let r = res.json::<FileUploadResponse>().await?;
-                Ok(r)
-            }
-            Err(e) => Err(e),
+    pub async fn file_upload(&self, req: FileUploadRequest) -> Result<FileUploadResponse, Error> {
+        let res = self.post("/files", &req).await?;
+        let r = res.json::<FileUploadResponse>().await;
+        match r {
+            Ok(r) => Ok(r),
+            Err(e) => Err(self.new_error(e)),
         }
     }
 
-    pub async fn file_delete(
-        &self,
-        req: FileDeleteRequest,
-    ) -> Result<FileDeleteResponse, Box<dyn std::error::Error>> {
-        let res = self.delete(&format!("{}/{}", "/files", req.file_id)).await;
-        match res {
-            Ok(res) => {
-                let r = res.json::<FileDeleteResponse>().await?;
-                Ok(r)
-            }
-            Err(e) => Err(e),
+    pub async fn file_delete(&self, req: FileDeleteRequest) -> Result<FileDeleteResponse, Error> {
+        let res = self
+            .delete(&format!("{}/{}", "/files", req.file_id))
+            .await?;
+        let r = res.json::<FileDeleteResponse>().await;
+        match r {
+            Ok(r) => Ok(r),
+            Err(e) => Err(self.new_error(e)),
         }
     }
 
     pub async fn file_retrieve(
         &self,
         req: FileRetrieveRequest,
-    ) -> Result<FileRetrieveResponse, Box<dyn std::error::Error>> {
-        let res = self.get(&format!("{}/{}", "/files", req.file_id)).await;
-        match res {
-            Ok(res) => {
-                let r = res.json::<FileRetrieveResponse>().await?;
-                Ok(r)
-            }
-            Err(e) => Err(e),
+    ) -> Result<FileRetrieveResponse, Error> {
+        let res = self.get(&format!("{}/{}", "/files", req.file_id)).await?;
+        let r = res.json::<FileRetrieveResponse>().await;
+        match r {
+            Ok(r) => Ok(r),
+            Err(e) => Err(self.new_error(e)),
         }
     }
 
     pub async fn file_retrieve_content(
         &self,
         req: FileRetrieveContentRequest,
-    ) -> Result<FileRetrieveContentResponse, Box<dyn std::error::Error>> {
+    ) -> Result<FileRetrieveContentResponse, Error> {
         let res = self
             .get(&format!("{}/{}/content", "/files", req.file_id))
-            .await;
-        match res {
-            Ok(res) => {
-                let r = res.json::<FileRetrieveContentResponse>().await?;
-                Ok(r)
-            }
-            Err(e) => Err(e),
+            .await?;
+        let r = res.json::<FileRetrieveContentResponse>().await;
+        match r {
+            Ok(r) => Ok(r),
+            Err(e) => Err(self.new_error(e)),
         }
     }
 
     pub async fn chat_completion(
         &self,
         req: ChatCompletionRequest,
-    ) -> Result<ChatCompletionResponse, Box<dyn std::error::Error>> {
-        let res = self.post("/chat/completions", &req).await;
-        match res {
-            Ok(res) => {
-                let r = res.json::<ChatCompletionResponse>().await?;
-                Ok(r)
-            }
-            Err(e) => Err(e),
+    ) -> Result<ChatCompletionResponse, Error> {
+        let res = self.post("/chat/completions", &req).await?;
+        let r = res.json::<ChatCompletionResponse>().await;
+        match r {
+            Ok(r) => Ok(r),
+            Err(e) => Err(self.new_error(e)),
         }
     }
+
+    fn new_error(&self, err: reqwest::Error) -> Error {
+        Error::new(std::io::ErrorKind::Other, err)
+    }
 }