diff --git a/src/client/response.rs b/src/client/response.rs
index 797c88df..41c18562 100644
--- a/src/client/response.rs
+++ b/src/client/response.rs
@@ -57,7 +57,7 @@ impl ClientResponse {
     /// Read the Request Version.
     #[inline]
     pub fn version(&self) -> Version {
-        self.head().version.clone().unwrap()
+        self.head().version
     }
 
     /// Get the status from the server.
diff --git a/src/h1/codec.rs b/src/h1/codec.rs
index a6f39242..bb8afa71 100644
--- a/src/h1/codec.rs
+++ b/src/h1/codec.rs
@@ -113,7 +113,6 @@ impl Codec {
             .unwrap_or_else(|| self.flags.contains(Flags::KEEPALIVE));
 
         // Connection upgrade
-        let version = msg.version().unwrap_or_else(|| self.version);
         if msg.upgrade() {
             self.flags.insert(Flags::UPGRADE);
             self.flags.remove(Flags::KEEPALIVE);
@@ -123,11 +122,11 @@ impl Codec {
         // keep-alive
         else if ka {
             self.flags.insert(Flags::KEEPALIVE);
-            if version < Version::HTTP_11 {
+            if self.version < Version::HTTP_11 {
                 msg.headers_mut()
                     .insert(CONNECTION, HeaderValue::from_static("keep-alive"));
             }
-        } else if version >= Version::HTTP_11 {
+        } else if self.version >= Version::HTTP_11 {
             self.flags.remove(Flags::KEEPALIVE);
             msg.headers_mut()
                 .insert(CONNECTION, HeaderValue::from_static("close"));
@@ -149,7 +148,7 @@ impl Codec {
             }
 
             // status line
-            helpers::write_status_line(version, msg.status().as_u16(), buffer);
+            helpers::write_status_line(self.version, msg.status().as_u16(), buffer);
             buffer.extend_from_slice(reason);
 
             // content length
diff --git a/src/h1/decoder.rs b/src/h1/decoder.rs
index 61cab7ad..26154ef1 100644
--- a/src/h1/decoder.rs
+++ b/src/h1/decoder.rs
@@ -290,7 +290,7 @@ impl MessageTypeDecoder for ClientResponse {
         };
 
         msg.head.status = status;
-        msg.head.version = Some(ver);
+        msg.head.version = ver;
 
         Ok(Some((msg, decoder)))
     }
diff --git a/src/h1/encoder.rs b/src/h1/encoder.rs
index 5cfdd01b..421d0b96 100644
--- a/src/h1/encoder.rs
+++ b/src/h1/encoder.rs
@@ -45,8 +45,6 @@ impl ResponseEncoder {
 
     pub fn update(&mut self, resp: &mut Response, head: bool, version: Version) {
         self.head = head;
-
-        let version = resp.version().unwrap_or_else(|| version);
         let mut len = 0;
 
         let has_body = match resp.body() {
diff --git a/src/message.rs b/src/message.rs
index f0275093..3dcb203d 100644
--- a/src/message.rs
+++ b/src/message.rs
@@ -53,7 +53,7 @@ impl Head for RequestHead {
 }
 
 pub struct ResponseHead {
-    pub version: Option<Version>,
+    pub version: Version,
     pub status: StatusCode,
     pub headers: HeaderMap,
     pub reason: Option<&'static str>,
@@ -63,7 +63,7 @@ pub struct ResponseHead {
 impl Default for ResponseHead {
     fn default() -> ResponseHead {
         ResponseHead {
-            version: None,
+            version: Version::default(),
             status: StatusCode::OK,
             headers: HeaderMap::with_capacity(16),
             reason: None,
@@ -75,7 +75,6 @@ impl Default for ResponseHead {
 impl Head for ResponseHead {
     fn clear(&mut self) {
         self.reason = None;
-        self.version = None;
         self.headers.clear();
         self.flags = MessageFlags::empty();
     }
diff --git a/src/response.rs b/src/response.rs
index 0b20f41b..f96facba 100644
--- a/src/response.rs
+++ b/src/response.rs
@@ -12,10 +12,10 @@ use http::{Error as HttpError, HeaderMap, HttpTryFrom, StatusCode, Version};
 use serde::Serialize;
 use serde_json;
 
-use message::{Head, ResponseHead, MessageFlags};
 use body::Body;
 use error::Error;
 use header::{ContentEncoding, Header, IntoHeaderValue};
+use message::{Head, MessageFlags, ResponseHead};
 
 /// max write buffer size 64k
 pub(crate) const MAX_WRITE_BUFFER_SIZE: usize = 65_536;
@@ -105,12 +105,6 @@ impl Response {
         self.get_ref().error.as_ref()
     }
 
-    /// Get the HTTP version of this response
-    #[inline]
-    pub fn version(&self) -> Option<Version> {
-        self.get_ref().head.version
-    }
-
     /// Get the headers from the response
     #[inline]
     pub fn headers(&self) -> &HeaderMap {
@@ -127,7 +121,12 @@ impl Response {
     #[inline]
     pub fn cookies(&self) -> CookieIter {
         CookieIter {
-            iter: self.get_ref().head.headers.get_all(header::SET_COOKIE).iter(),
+            iter: self
+                .get_ref()
+                .head
+                .headers
+                .get_all(header::SET_COOKIE)
+                .iter(),
         }
     }
 
@@ -187,7 +186,8 @@ impl Response {
             reason
         } else {
             self.get_ref()
-                .head.status
+                .head
+                .status
                 .canonical_reason()
                 .unwrap_or("<unknown status code>")
         }
@@ -347,17 +347,6 @@ impl ResponseBuilder {
         self
     }
 
-    /// Set HTTP version of this response.
-    ///
-    /// By default response's http version depends on request's version.
-    #[inline]
-    pub fn version(&mut self, version: Version) -> &mut Self {
-        if let Some(parts) = parts(&mut self.response, &self.err) {
-            parts.head.version = Some(version);
-        }
-        self
-    }
-
     /// Set a header.
     ///
     /// ```rust,ignore
@@ -782,11 +771,15 @@ pub(crate) struct ResponseParts {
 
 impl InnerResponse {
     #[inline]
-    fn new(status: StatusCode, body: Body, pool: &'static ResponsePool) -> InnerResponse {
+    fn new(
+        status: StatusCode,
+        body: Body,
+        pool: &'static ResponsePool,
+    ) -> InnerResponse {
         InnerResponse {
             head: ResponseHead {
                 status,
-                version: None,
+                version: Version::default(),
                 headers: HeaderMap::with_capacity(16),
                 reason: None,
                 flags: MessageFlags::empty(),
@@ -999,11 +992,7 @@ mod tests {
 
     #[test]
     fn test_basic_builder() {
-        let resp = Response::Ok()
-            .header("X-TEST", "value")
-            .version(Version::HTTP_10)
-            .finish();
-        assert_eq!(resp.version(), Some(Version::HTTP_10));
+        let resp = Response::Ok().header("X-TEST", "value").finish();
         assert_eq!(resp.status(), StatusCode::OK);
     }