diff --git a/CHANGELOG.md b/CHANGELOG.md
index b1bb2a61..1d5c2c45 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,3 +1,8 @@
+# 0.6.0
+
+Upgrade step 2 of 4. This version sets the non-standard flag, version 0.5.0
+already recognises.
+
 # 0.5.0
 
 This version begins the upgrade process spawning multiple versions that
diff --git a/Cargo.toml b/Cargo.toml
index db2bb82a..d8855d02 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -1,6 +1,6 @@
 [package]
 name = "yamux"
-version = "0.5.0"
+version = "0.6.0"
 authors = ["Parity Technologies <admin@parity.io>"]
 license = "Apache-2.0 OR MIT"
 description = "Multiplexer over reliable, ordered connections"
diff --git a/src/connection.rs b/src/connection.rs
index 20b2a882..aae4f76a 100644
--- a/src/connection.rs
+++ b/src/connection.rs
@@ -463,23 +463,20 @@ impl<T: AsyncRead + AsyncWrite + Unpin> Connection<T> {
                 }
                 log::trace!("{}: creating new outbound stream", self.id);
                 let id = self.next_stream_id()?;
-                if !self.config.lazy_open {
-                    let mut frame = Frame::window_update(id, self.config.receive_window);
+                let extra_credit = self.config.receive_window - DEFAULT_CREDIT;
+                if extra_credit > 0 {
+                    let mut frame = Frame::window_update(id, extra_credit);
                     frame.header_mut().syn();
+                    frame.header_mut().additive();
                     log::trace!("{}: sending initial {}", self.id, frame.header());
                     self.socket.get_mut().send(&frame).await.or(Err(ConnectionError::Closed))?
                 }
                 let stream = {
                     let config = self.config.clone();
                     let sender = self.stream_sender.clone();
-                    let window =
-                        if self.config.lazy_open {
-                            DEFAULT_CREDIT
-                        } else {
-                            self.config.receive_window
-                        };
+                    let window = self.config.receive_window;
                     let mut stream = Stream::new(id, self.id, config, window, DEFAULT_CREDIT, sender);
-                    if self.config.lazy_open {
+                    if extra_credit == 0 {
                         stream.set_flag(stream::Flag::Syn)
                     }
                     stream
@@ -489,7 +486,7 @@ impl<T: AsyncRead + AsyncWrite + Unpin> Connection<T> {
                     self.streams.insert(id, stream);
                 } else {
                     log::debug!("{}: open stream {} has been cancelled", self.id, id);
-                    if !self.config.lazy_open {
+                    if extra_credit > 0 {
                         let mut header = Header::data(id, 0);
                         header.rst();
                         let frame = Frame::new(header);
diff --git a/src/frame/header.rs b/src/frame/header.rs
index a0538c25..2e4bb7aa 100644
--- a/src/frame/header.rs
+++ b/src/frame/header.rs
@@ -99,6 +99,11 @@ impl<T: HasSyn> Header<T> {
     pub fn syn(&mut self) {
         self.flags.0 |= SYN.0
     }
+
+    /// Set the [`ADD`] flag.
+    pub fn additive(&mut self) {
+        self.flags.0 |= ADD.0
+    }
 }
 
 impl<T: HasAck> Header<T> {
diff --git a/src/lib.rs b/src/lib.rs
index c6d7bd32..bbb162fd 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -76,15 +76,13 @@ pub enum WindowUpdateMode {
 /// - max. number of streams = 8192
 /// - window update mode = on receive
 /// - read after close = true
-/// - lazy open = false
 #[derive(Debug, Clone)]
 pub struct Config {
     receive_window: u32,
     max_buffer_size: usize,
     max_num_streams: usize,
     window_update_mode: WindowUpdateMode,
-    read_after_close: bool,
-    lazy_open: bool
+    read_after_close: bool
 }
 
 impl Default for Config {
@@ -94,8 +92,7 @@ impl Default for Config {
             max_buffer_size: 1024 * 1024,
             max_num_streams: 8192,
             window_update_mode: WindowUpdateMode::OnReceive,
-            read_after_close: true,
-            lazy_open: false
+            read_after_close: true
         }
     }
 }
@@ -149,8 +146,8 @@ impl Config {
     /// to the remote. This allows opening a stream with a custom receive
     /// window size (cf. [`Config::set_receive_window`]) which the remote
     /// can directly make use of.
-    pub fn set_lazy_open(&mut self, b: bool) -> &mut Self {
-        self.lazy_open = b;
+    #[deprecated(since = "0.6.0")]
+    pub fn set_lazy_open(&mut self, _: bool) -> &mut Self {
         self
     }
 }
diff --git a/src/tests.rs b/src/tests.rs
index 6a3a7998..fc661a68 100644
--- a/src/tests.rs
+++ b/src/tests.rs
@@ -221,7 +221,6 @@ impl Arbitrary for TestConfig {
         } else {
             WindowUpdateMode::OnReceive
         });
-        c.set_lazy_open(g.gen());
         c.set_read_after_close(g.gen());
         c.set_receive_window(g.gen_range(256 * 1024, 1024 * 1024));
         TestConfig(c)