diff --git a/actix-http/CHANGES.md b/actix-http/CHANGES.md
index c5c02865..79187e7a 100644
--- a/actix-http/CHANGES.md
+++ b/actix-http/CHANGES.md
@@ -6,6 +6,8 @@
 
 * Rust 1.31.0 compatibility
 
+* Preallocate read buffer for h1 codec
+
 
 ## [0.1.0-alpha.2] - 2019-03-29
 
diff --git a/actix-http/Cargo.toml b/actix-http/Cargo.toml
index 2de624b7..a9fda44e 100644
--- a/actix-http/Cargo.toml
+++ b/actix-http/Cargo.toml
@@ -1,6 +1,6 @@
 [package]
 name = "actix-http"
-version = "0.1.0-alpha.2"
+version = "0.1.0-alpha.3"
 authors = ["Nikolay Kim <fafhrd91@gmail.com>"]
 description = "Actix http primitives"
 readme = "README.md"
diff --git a/actix-http/src/h1/codec.rs b/actix-http/src/h1/codec.rs
index ceb1027e..e4895f2d 100644
--- a/actix-http/src/h1/codec.rs
+++ b/actix-http/src/h1/codec.rs
@@ -19,6 +19,9 @@ use crate::message::{ConnectionType, Head, ResponseHead};
 use crate::request::Request;
 use crate::response::Response;
 
+const LW: usize = 2 * 1024;
+const HW: usize = 32 * 1024;
+
 bitflags! {
     struct Flags: u8 {
         const HEAD              = 0b0000_0001;
@@ -105,6 +108,11 @@ impl Decoder for Codec {
     type Error = ParseError;
 
     fn decode(&mut self, src: &mut BytesMut) -> Result<Option<Self::Item>, Self::Error> {
+        let cap = src.capacity();
+        if cap < LW {
+            src.reserve(HW - cap);
+        }
+
         if self.payload.is_some() {
             Ok(match self.payload.as_mut().unwrap().decode(src)? {
                 Some(PayloadItem::Chunk(chunk)) => Some(Message::Chunk(Some(chunk))),