diff --git a/CHANGELOG.md b/CHANGELOG.md
index 6d45b13c..b22fe7d3 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -12,6 +12,7 @@ API Changes:
 
 * parser requires basic_fields
 * Refine FieldsReader concept
+* message::prepare_payload replaces message::prepare
 
 Actions Required:
 
@@ -21,6 +22,10 @@ Actions Required:
 
 * Implement chunked() and keep_alive() for user defined FieldsReader types.
 
+* Change calls to msg.prepare to msg.prepare_payload. For messages
+  with a user-defined Fields, provide the function prepare_payload_impl
+  in the fields type according to the Fields requirements.
+
 --------------------------------------------------------------------------------
 
 Version 61:
diff --git a/doc/5_02_message.qbk b/doc/5_02_message.qbk
index f9391bbd..ab2a22df 100644
--- a/doc/5_02_message.qbk
+++ b/doc/5_02_message.qbk
@@ -151,7 +151,7 @@ request.
 
 Here we create an HTTP response indicating success. Note that this
 message has a body. The function
-[link beast.ref.beast__http__message.prepare prepare]
+[link beast.ref.beast__http__message.prepare_payload `message::prepare_payload`]
 automatically sets the Content-Length or Transfer-Encoding field
 depending on the content and type of the `body` member. The use
 of prepare is optional; these fields may also be set explicitly.
diff --git a/doc/concept/Body.qbk b/doc/concept/Body.qbk
index 15bcab8c..006600d8 100644
--- a/doc/concept/Body.qbk
+++ b/doc/concept/Body.qbk
@@ -53,7 +53,7 @@ In this table:
     [
         If present, returns the serialized size of `v` not including
         any chunked transfer encoding. When this function is provided,
-        [link beast.ref.beast__http__message.prepare `message::prepare`]
+        [link beast.ref.beast__http__message.prepare_payload `message::prepare_payload`]
         will automatically set the content length field based on the
         value. Otherwise, the chunked transfer encoding will be set.
     ]
diff --git a/doc/concept/Fields.qbk b/doc/concept/Fields.qbk
index 9d4497ad..b97afa9d 100644
--- a/doc/concept/Fields.qbk
+++ b/doc/concept/Fields.qbk
@@ -25,6 +25,10 @@ In this table:
 
 * `s` is a value of type [link beast.ref.beast__string_view `string_view`].
 
+* `b` is a value of type `bool`
+
+* `n` is a value of type `boost::optional<std::uint64_t>`.
+
 [table Fields requirements
 [[expression][type][semantics, pre/post-conditions]]
 [
@@ -88,6 +92,29 @@ In this table:
         This function may throw `std::invalid_argument` if the operation
         is not supported by the container.
     ]
+][
+    [`a.prepare_payload_impl(b,n)`]
+    []
+    [
+        Adjusts the Content-Length and Transfer-Encoding fields to
+        account for the payload metadata indicated by `b` and `n` as
+        follows:
+
+        * If `b` is `true`, the chunked Transfer-Encoding should be applied
+        to the end of the list of encodings if it is not already there
+        or if the field was not present. Any Content-Length fields should
+        be removed.
+
+        * If `b` is `false` and `n` contains a value, set the Content-Length
+        field to `*n`, replacing any previous Content-Length fields. Remove
+        the chunked encoding from the end of the Transfer-Encoding field
+        if the field is present ahd chunked is the last encoding.
+
+        * If `b` is `false` and `n` contains no value, remove all Content-Length
+        fields, and remove the chunked encoding from the end of the
+        Transfer-Encoding field if the field is present ahd chunked is the
+        last encoding.
+    ]
 ]
 ]
 
@@ -132,6 +159,14 @@ protected:
         @note Only called for responses.
     */
     string_view get_reason_impl() const;
+
+    /** Updates the payload metadata.
+
+        @param b `true` if chunked
+
+        @param n The content length if known, otherwise `boost::none`
+    */
+    void prepare_payload_impl(bool b, boost::optional<std::uint64_t> n)
 };
 ```
 
diff --git a/example/doc/http_examples.hpp b/example/doc/http_examples.hpp
index 6279fb73..5716fbb1 100644
--- a/example/doc/http_examples.hpp
+++ b/example/doc/http_examples.hpp
@@ -320,7 +320,7 @@ void do_server_head(
         // set of headers that would be sent for a GET request,
         // including the Content-Length, except for the body.
         res.result(status::ok);
-        res.content_length(payload.size());
+        res.set(field::content_length, payload.size());
 
         // For GET requests, we include the body
         if(req.method() == verb::get)
diff --git a/example/http-client-ssl/http_client_ssl.cpp b/example/http-client-ssl/http_client_ssl.cpp
index 8c5cab72..59bcb83d 100644
--- a/example/http-client-ssl/http_client_ssl.cpp
+++ b/example/http-client-ssl/http_client_ssl.cpp
@@ -64,7 +64,7 @@ int main()
     req.set(http::field::host, host + ":" +
         boost::lexical_cast<std::string>(sock.remote_endpoint().port()));
     req.set(http::field::user_agent, "Beast");
-    req.prepare();
+    req.prepare_payload();
 
     // Write the HTTP request to the remote host
     http::write(stream, req, ec);
diff --git a/example/http-client/http_client.cpp b/example/http-client/http_client.cpp
index a17ddb9d..fe405462 100644
--- a/example/http-client/http_client.cpp
+++ b/example/http-client/http_client.cpp
@@ -55,7 +55,7 @@ int main()
     req.set(http::field::host, host + ":" +
         boost::lexical_cast<std::string>(sock.remote_endpoint().port()));
     req.set(http::field::user_agent, "Beast");
-    req.prepare();
+    req.prepare_payload();
 
     // Write the HTTP request to the remote host
     http::write(sock, req, ec);
diff --git a/example/server-framework/file_service.hpp b/example/server-framework/file_service.hpp
index 1b29f8eb..2fa2b1ca 100644
--- a/example/server-framework/file_service.hpp
+++ b/example/server-framework/file_service.hpp
@@ -225,7 +225,7 @@ private:
         res.set(beast::http::field::server, server_);
         res.set(beast::http::field::content_type, "text/html");
         res.body = "The file was not found"; // VFALCO append rel_path
-        res.prepare();
+        res.prepare_payload();
         return res;
     }
 
@@ -243,7 +243,7 @@ private:
         res.set(beast::http::field::server, server_);
         res.set(beast::http::field::content_type, mime_type(full_path));
         res.body = full_path;
-        res.prepare();
+        res.prepare_payload();
         return res;
     }
 
diff --git a/example/server-framework/http_base.hpp b/example/server-framework/http_base.hpp
index aa95cd4f..6dddb079 100644
--- a/example/server-framework/http_base.hpp
+++ b/example/server-framework/http_base.hpp
@@ -50,7 +50,7 @@ protected:
         res.set(beast::http::field::server, server_name_);
         res.set(beast::http::field::content_type, "text/html");
         res.body = "Bad request";
-        res.prepare();
+        res.prepare_payload();
         return res;
     }
 
diff --git a/include/beast/http/empty_body.hpp b/include/beast/http/empty_body.hpp
index 684cac53..8ee8bb71 100644
--- a/include/beast/http/empty_body.hpp
+++ b/include/beast/http/empty_body.hpp
@@ -38,7 +38,7 @@ struct empty_body
     /// Returns the content length of the body in a message.
     static
     std::uint64_t
-    size(empty_body)
+    size(value_type)
     {
         return 0;
     }
diff --git a/include/beast/http/fields.hpp b/include/beast/http/fields.hpp
index 418cd989..623508f3 100644
--- a/include/beast/http/fields.hpp
+++ b/include/beast/http/fields.hpp
@@ -15,6 +15,7 @@
 #include <boost/asio/buffer.hpp>
 #include <boost/intrusive/list.hpp>
 #include <boost/intrusive/set.hpp>
+#include <boost/optional.hpp>
 #include <algorithm>
 #include <cctype>
 #include <cstring>
@@ -39,7 +40,6 @@ namespace http {
     as a `std::multiset`; there will be a separate value for each occurrence
     of the field name.
 
-
     Meets the requirements of @b Fields
 
     @tparam Allocator The allocator to use. This must meet the
@@ -48,7 +48,7 @@ namespace http {
 template<class Allocator>
 class basic_fields
 {
-    static std::size_t constexpr max_static_start_line = 4096;
+    static std::size_t constexpr max_static_buffer = 4096;
 
     using off_t = std::uint16_t;
 
@@ -591,22 +591,11 @@ protected:
     */
     string_view get_reason_impl() const;
 
-    //--------------------------------------------------------------------------
-    //
-    // for container
-    //
-
-    /** Set the Content-Length field to the specified value.
-
-        @note This is called by the @ref header implementation.
+    /** Adjusts the payload related fields
     */
-    void content_length_impl(std::uint64_t n);
-
-    /** Add chunked to the Transfer-Encoding field.
-
-        @note This is called by the @ref header implementation.
-    */
-    void set_chunked_impl(bool v);
+    void
+    prepare_payload_impl(bool chunked,
+        boost::optional<std::uint64_t> size);
 
 private:
     template<class OtherAlloc>
diff --git a/include/beast/http/impl/fields.ipp b/include/beast/http/impl/fields.ipp
index 64cf1efc..bbfce4ce 100644
--- a/include/beast/http/impl/fields.ipp
+++ b/include/beast/http/impl/fields.ipp
@@ -9,6 +9,7 @@
 #define BEAST_HTTP_IMPL_FIELDS_IPP
 
 #include <beast/core/buffer_cat.hpp>
+#include <beast/core/string.hpp>
 #include <beast/core/static_string.hpp>
 #include <beast/http/verb.hpp>
 #include <beast/http/rfc7230.hpp>
@@ -149,7 +150,7 @@ public:
         unsigned version, unsigned code);
 
     basic_fields const& f_;
-    static_string<max_static_start_line> ss_;
+    static_string<max_static_buffer> ss_;
     string_view sv_;
     std::string s_;
     bool chunked_;
@@ -199,7 +200,7 @@ get_chunked() const
         f_[field::transfer_encoding]};
     for(auto it = te.begin(); it != te.end();)
     {
-        auto next = std::next(it);
+        auto const next = std::next(it);
         if(next == te.end())
             return iequals(*it, "chunked");
         it = next;
@@ -866,32 +867,119 @@ get_reason_impl() const
     return target_or_reason_;
 }
 
-//---
+namespace detail {
 
-template<class Allocator>
-inline
+// Builds a new string with "chunked" maybe taken off the end
+template<class String>
 void
-basic_fields<Allocator>::
-content_length_impl(std::uint64_t n)
+without_chunked_last(String& s, string_view const& tokens)
 {
-    erase(field::content_length);
-    insert(field::content_length, n);
+    token_list te{tokens};
+    if(te.begin() != te.end())
+    {
+        auto it = te.begin();
+        auto next = std::next(it);
+        if(next == te.end())
+        {
+            if(! iequals(*it, "chunked"))
+                s.append(it->data(), it->size());
+            return;
+        }
+        s.append(it->data(), it->size());
+        for(;;)
+        {
+            it = next;
+            next = std::next(it);
+            if(next == te.end())
+            {
+                if(! iequals(*it, "chunked"))
+                {
+                    s.append(", ");
+                    s.append(it->data(), it->size());
+                }
+                return;
+            }
+            s.append(", ");
+            s.append(it->data(), it->size());
+        }
+    }
 }
 
+} // detail
+
 template<class Allocator>
-inline
 void
 basic_fields<Allocator>::
-set_chunked_impl(bool v)
+prepare_payload_impl(bool chunked,
+    boost::optional<std::uint64_t> size)
 {
-    // VFALCO We need to handle removing the chunked as well
-    BOOST_ASSERT(v);
-    auto it = find(field::transfer_encoding);
-    if(it == end())
-        insert(field::transfer_encoding, "chunked");
+    if(chunked)
+    {
+        BOOST_ASSERT(! size);
+        erase(field::content_length);
+        auto it = find(field::transfer_encoding);
+        if(it == end())
+        {
+            set(field::transfer_encoding, "chunked");
+            return;
+        }
+
+        static_string<max_static_buffer> temp;
+        if(it->value().size() <= temp.size() + 9)
+        {
+            temp.append(it->value().data(), it->value().size());
+            temp.append(", chunked", 9);
+            set(field::transfer_encoding, temp);
+        }
+        else
+        {
+            std::string s;
+            s.reserve(it->value().size() + 9);
+            s.append(it->value().data(), it->value().size());
+            s.append(", chunked", 9);
+            set(field::transfer_encoding, s);
+        }
+        return;
+    }
+    auto const clear_chunked =
+        [this]()
+        {
+            auto it = find(field::transfer_encoding);
+            if(it == end())
+                return;
+
+            // We have to just try it because we can't
+            // know ahead of time if there's enough room.
+            try
+            {
+                static_string<max_static_buffer> temp;
+                detail::without_chunked_last(temp, it->value());
+                if(! temp.empty())
+                    set(field::transfer_encoding, temp);
+                else
+                    erase(field::transfer_encoding);
+            }
+            catch(std::length_error const&)
+            {
+                std::string s;
+                s.reserve(it->value().size());
+                detail::without_chunked_last(s, it->value());
+                if(! s.empty())
+                    set(field::transfer_encoding, s);
+                else
+                    erase(field::transfer_encoding);
+            }
+        };
+    if(size)
+    {
+        clear_chunked();
+        set(field::content_length, *size);
+    }
     else
-        set(field::transfer_encoding,
-            it->value().to_string() + ", chunked");
+    {
+        clear_chunked();
+        erase(field::content_length);
+    }
 }
 
 //------------------------------------------------------------------------------
diff --git a/include/beast/http/impl/message.ipp b/include/beast/http/impl/message.ipp
index 4660b2a1..37216f03 100644
--- a/include/beast/http/impl/message.ipp
+++ b/include/beast/http/impl/message.ipp
@@ -252,69 +252,53 @@ message(std::piecewise_construct_t,
 template<bool isRequest, class Body, class Fields>
 boost::optional<std::uint64_t>
 message<isRequest, Body, Fields>::
-size() const
+payload_size() const
 {
-    static_assert(is_body_reader<Body>::value,
-        "BodyReader requirements not met");
-
-    return size(detail::is_body_sized<Body>{});
+    return payload_size(detail::is_body_sized<Body>{});
 }
 
 template<bool isRequest, class Body, class Fields>
 void
 message<isRequest, Body, Fields>::
-content_length(std::uint64_t n)
+prepare_payload(std::true_type)
 {
-    this->content_length_impl(n);
-}
-
-template<bool isRequest, class Body, class Fields>
-void
-message<isRequest, Body, Fields>::
-prepare()
-{
-    prepare(typename header_type::is_request{});
-}
-
-template<bool isRequest, class Body, class Fields>
-inline
-void
-message<isRequest, Body, Fields>::
-prepare(std::true_type)
-{
-    auto const n = size();
-    if(this->method_ == verb::trace && (
-            ! n || *n > 0))
+    auto const n = payload_size();
+    if(this->method() == verb::trace && (! n || *n > 0))
         BOOST_THROW_EXCEPTION(std::invalid_argument{
             "invalid request body"});
     if(n)
     {
         if(*n > 0 ||
-            this->method_ == verb::options ||
-            this->method_ == verb::put ||
-            this->method_ == verb::post
-            )
+            this->method() == verb::options ||
+            this->method() == verb::put ||
+            this->method() == verb::post)
         {
-            this->content_length_impl(*n);
+            this->prepare_payload_impl(false, *n);
+        }
+        else
+        {
+            this->prepare_payload_impl(false, boost::none);
         }
     }
     else if(this->version >= 11)
     {
-        this->set_chunked_impl(true);
+        this->prepare_payload_impl(true, boost::none);
+    }
+    else
+    {
+        this->prepare_payload_impl(false, boost::none);
     }
 }
 
 template<bool isRequest, class Body, class Fields>
-inline
 void
 message<isRequest, Body, Fields>::
-prepare(std::false_type)
+prepare_payload(std::false_type)
 {
-    auto const n = size();
-    if((status_class(this->result_) ==
-            status_class::informational ||
-        this->result_ == status::no_content ||
-        this->result_ == status::not_modified))
+    auto const n = payload_size();
+    if((status_class(this->result()) == status_class::informational ||
+        this->result() == status::no_content ||
+        this->result() == status::not_modified))
     {
         if(! n || *n > 0)
             // The response body MUST BE empty for this case
@@ -322,9 +306,13 @@ prepare(std::false_type)
                 "invalid response body"});
     }
     if(n)
-        this->content_length_impl(*n);
-    else if(this->version >= 11)
-        this->set_chunked_impl(true);
+    {
+        this->prepare_payload_impl(false, *n);
+    }
+    else
+    {
+        this->prepare_payload_impl(true, boost::none);
+    }
 }
 
 //------------------------------------------------------------------------------
diff --git a/include/beast/http/message.hpp b/include/beast/http/message.hpp
index 827f3618..f0e821c7 100644
--- a/include/beast/http/message.hpp
+++ b/include/beast/http/message.hpp
@@ -496,17 +496,8 @@ struct message : header<isRequest, Fields>
         is not inspected.
     */
     boost::optional<std::uint64_t>
-    size() const;
+    payload_size() const;
 
-    /** Set the Content-Length field.
-
-        The value of the Content-Length field will be unconditionally
-        set to the specified number of octets.
-
-        @param n The number of octets to set for the Content-Length field.
-    */
-    void
-    content_length(std::uint64_t n);
 
     /** Prepare the message payload fields for the body.
 
@@ -522,11 +513,14 @@ struct message : header<isRequest, Fields>
         req.target("/");
         req.set(field::user_agent, "Beast");
         req.body = "Hello, world!";
-        req.prepare();
+        req.prepare_payload();
         @endcode
     */
     void
-    prepare();
+    prepare_payload()
+    {
+        prepare_payload(typename header_type::is_request{});
+    }
 
 private:
     static_assert(is_body<Body>::value,
@@ -552,22 +546,22 @@ private:
     }
 
     boost::optional<std::uint64_t>
-    size(std::true_type) const
+    payload_size(std::true_type) const
     {
         return Body::size(body);
     }
 
     boost::optional<std::uint64_t>
-    size(std::false_type) const
+    payload_size(std::false_type) const
     {
         return boost::none;
     }
 
     void
-    prepare(std::true_type);
+    prepare_payload(std::true_type);
 
     void
-    prepare(std::false_type);
+    prepare_payload(std::false_type);
 };
 
 /// A typical HTTP request
diff --git a/include/beast/websocket/impl/stream.ipp b/include/beast/websocket/impl/stream.ipp
index a12bfbb7..048f4fc0 100644
--- a/include/beast/websocket/impl/stream.ipp
+++ b/include/beast/websocket/impl/stream.ipp
@@ -218,7 +218,7 @@ build_response(http::header<true,
             res.version = req.version;
             res.result(http::status::bad_request);
             res.body = text;
-            res.prepare();
+            res.prepare_payload();
             decorate(res);
             return res;
         };
@@ -248,7 +248,7 @@ build_response(http::header<true,
             res.result(http::status::upgrade_required);
             res.version = req.version;
             res.set(http::field::sec_websocket_version, "13");
-            res.prepare();
+            res.prepare_payload();
             decorate(res);
             return res;
         }
diff --git a/test/http/doc_examples.cpp b/test/http/doc_examples.cpp
index d0f0406d..7b80a6f0 100644
--- a/test/http/doc_examples.cpp
+++ b/test/http/doc_examples.cpp
@@ -73,7 +73,7 @@ public:
                 req.target("/");
                 req.insert(field::user_agent, "test");
                 req.body = "Hello, world!";
-                req.prepare();
+                req.prepare_payload();
 
                 error_code ec;
                 send_expect_100_continue(
@@ -106,7 +106,7 @@ public:
         req.target("/");
         req.insert(field::user_agent, "test");
         req.body = "Hello, world!";
-        req.prepare();
+        req.prepare_payload();
 
         test::pipe downstream{ios_};
         downstream.server.read_size(3);
@@ -272,7 +272,7 @@ public:
             req.method(verb::put);
             req.target("/");
             req.body = body;
-            req.prepare();
+            req.prepare_payload();
             write(c.client, req);
         }
         {
@@ -293,7 +293,7 @@ public:
             res.result(status::ok);
             res.insert(field::server, "test");
             res.body = path;
-            res.prepare();
+            res.prepare_payload();
             write(c.server, res);
         }
         {
diff --git a/test/http/doc_snippets.cpp b/test/http/doc_snippets.cpp
index 5fc1bac9..99e7418f 100644
--- a/test/http/doc_snippets.cpp
+++ b/test/http/doc_snippets.cpp
@@ -49,7 +49,7 @@ void fxx() {
     res.result(status::ok);
     res.set(field::server, "Beast");
     res.body = "Hello, world!";
-    res.prepare();
+    res.prepare_payload();
 
 //]
 }
diff --git a/test/http/fields.cpp b/test/http/fields.cpp
index d7f2c0e7..c0b9f55b 100644
--- a/test/http/fields.cpp
+++ b/test/http/fields.cpp
@@ -8,6 +8,8 @@
 // Test that header file is self-contained.
 #include <beast/http/fields.hpp>
 
+#include <beast/http/empty_body.hpp>
+#include <beast/http/message.hpp>
 #include <beast/test/test_allocator.hpp>
 #include <beast/unit_test/suite.hpp>
 #include <boost/lexical_cast.hpp>
@@ -397,6 +399,188 @@ public:
         }
     }
 
+    struct sized_body
+    {
+        using value_type = std::uint64_t;
+
+        static
+        std::uint64_t
+        size(value_type const& v)
+        {
+            return v;
+        }
+    };
+
+    struct unsized_body
+    {
+        struct value_type {};
+    };
+
+    void
+    testPreparePayload()
+    {
+        // GET, empty
+        {
+            request<empty_body> req;
+            req.version = 11;
+            req.method(verb::get);
+
+            req.prepare_payload();
+            BEAST_EXPECT(req.count(field::content_length) == 0);
+            BEAST_EXPECT(req.count(field::transfer_encoding) == 0);
+
+            req.set(field::content_length, "0");
+            req.set(field::transfer_encoding, "chunked");
+            req.prepare_payload();
+
+            BEAST_EXPECT(req.count(field::content_length) == 0);
+            BEAST_EXPECT(req.count(field::transfer_encoding) == 0);
+
+            req.set(field::transfer_encoding, "deflate");
+            req.prepare_payload();
+            BEAST_EXPECT(req.count(field::content_length) == 0);
+            BEAST_EXPECT(req[field::transfer_encoding] == "deflate");
+
+            req.set(field::transfer_encoding, "deflate, chunked");
+            req.prepare_payload();
+            BEAST_EXPECT(req.count(field::content_length) == 0);
+            BEAST_EXPECT(req[field::transfer_encoding] == "deflate");
+        }
+
+        // GET, sized
+        {
+            request<sized_body> req;
+            req.version = 11;
+            req.method(verb::get);
+            req.body = 50;
+
+            req.prepare_payload();
+            BEAST_EXPECT(req[field::content_length] == "50");
+            BEAST_EXPECT(req[field::transfer_encoding] == "");
+
+            req.set(field::content_length, "0");
+            req.set(field::transfer_encoding, "chunked");
+            req.prepare_payload();
+            BEAST_EXPECT(req[field::content_length] == "50");
+            BEAST_EXPECT(req.count(field::transfer_encoding) == 0);
+
+            req.set(field::transfer_encoding, "deflate, chunked");
+            req.prepare_payload();
+            BEAST_EXPECT(req[field::content_length] == "50");
+            BEAST_EXPECT(req[field::transfer_encoding] == "deflate");
+        }
+
+        // PUT, empty
+        {
+            request<empty_body> req;
+            req.version = 11;
+            req.method(verb::put);
+
+            req.prepare_payload();
+            BEAST_EXPECT(req[field::content_length] == "0");
+            BEAST_EXPECT(req.count(field::transfer_encoding) == 0);
+
+            req.set(field::content_length, "50");
+            req.set(field::transfer_encoding, "deflate, chunked");
+            req.prepare_payload();
+            BEAST_EXPECT(req[field::content_length] == "0");
+            BEAST_EXPECT(req[field::transfer_encoding] == "deflate");
+        }
+
+        // PUT, sized
+        {
+            request<sized_body> req;
+            req.version = 11;
+            req.method(verb::put);
+            req.body = 50;
+
+            req.prepare_payload();
+            BEAST_EXPECT(req[field::content_length] == "50");
+            BEAST_EXPECT(req.count(field::transfer_encoding) == 0);
+
+            req.set(field::content_length, "25");
+            req.set(field::transfer_encoding, "deflate, chunked");
+            req.prepare_payload();
+            BEAST_EXPECT(req[field::content_length] == "50");
+            BEAST_EXPECT(req[field::transfer_encoding] == "deflate");
+        }
+
+        // POST, unsized
+        {
+            request<unsized_body> req;
+            req.version = 11;
+            req.method(verb::post);
+
+            req.prepare_payload();
+            BEAST_EXPECT(req.count(field::content_length) == 0);
+            BEAST_EXPECT(req[field::transfer_encoding] == "chunked");
+
+            req.set(field::transfer_encoding, "deflate");
+            req.prepare_payload();
+            BEAST_EXPECT(req.count(field::content_length) == 0);
+            BEAST_EXPECT(req[field::transfer_encoding] == "deflate, chunked");
+        }
+
+        // POST, unsized HTTP/1.0
+        {
+            request<unsized_body> req;
+            req.version = 10;
+            req.method(verb::post);
+
+            req.prepare_payload();
+            BEAST_EXPECT(req.count(field::content_length) == 0);
+            BEAST_EXPECT(req.count(field::transfer_encoding) == 0);
+
+            req.set(field::transfer_encoding, "deflate");
+            req.prepare_payload();
+            BEAST_EXPECT(req.count(field::content_length) == 0);
+            BEAST_EXPECT(req[field::transfer_encoding] == "deflate");
+        }
+
+        // OK, empty
+        {
+            response<empty_body> res;
+            res.version = 11;
+
+            res.prepare_payload();
+            BEAST_EXPECT(res[field::content_length] == "0");
+            BEAST_EXPECT(res.count(field::transfer_encoding) == 0);
+
+            res.erase(field::content_length);
+            res.set(field::transfer_encoding, "chunked");
+            res.prepare_payload();
+            BEAST_EXPECT(res[field::content_length] == "0");
+            BEAST_EXPECT(res.count(field::transfer_encoding) == 0);
+        }
+
+        // OK, sized
+        {
+            response<sized_body> res;
+            res.version = 11;
+            res.body = 50;
+
+            res.prepare_payload();
+            BEAST_EXPECT(res[field::content_length] == "50");
+            BEAST_EXPECT(res.count(field::transfer_encoding) == 0);
+
+            res.erase(field::content_length);
+            res.set(field::transfer_encoding, "chunked");
+            res.prepare_payload();
+            BEAST_EXPECT(res[field::content_length] == "50");
+            BEAST_EXPECT(res.count(field::transfer_encoding) == 0);
+        }
+
+        // OK, unsized
+        {
+            response<unsized_body> res;
+            res.version = 11;
+
+            res.prepare_payload();
+            BEAST_EXPECT(res.count(field::content_length) == 0);
+            BEAST_EXPECT(res[field::transfer_encoding] == "chunked");
+        }
+    }
+
     void run() override
     {
         testMembers();
@@ -404,6 +588,7 @@ public:
         testRFC2616();
         testErase();
         testContainer();
+        testPreparePayload();
     }
 };
 
diff --git a/test/http/string_view_body.cpp b/test/http/string_view_body.cpp
index 3f5eb1a7..f709a8b9 100644
--- a/test/http/string_view_body.cpp
+++ b/test/http/string_view_body.cpp
@@ -31,7 +31,7 @@ public:
         req.version = 11;
         req.method(verb::post);
         req.target("/");
-        req.prepare();
+        req.prepare_payload();
         static_buffer_n<512> b;
         ostream(b) << req;
         string_view const s{
diff --git a/test/http/write.cpp b/test/http/write.cpp
index 6846eb88..0bccb8dd 100644
--- a/test/http/write.cpp
+++ b/test/http/write.cpp
@@ -532,7 +532,7 @@ public:
             m.version = 10;
             m.insert(field::user_agent, "test");
             m.body = "*";
-            m.prepare();
+            m.prepare_payload();
             BEAST_EXPECT(str(m) ==
                 "GET / HTTP/1.0\r\n"
                 "User-Agent: test\r\n"
@@ -549,7 +549,7 @@ public:
             m.version = 10;
             m.insert(field::user_agent, "test");
             m.body = "*";
-            m.prepare();
+            m.prepare_payload();
             test::string_ostream ss(ios_);
             error_code ec;
             write(ss, m, ec);
@@ -569,7 +569,7 @@ public:
             m.version = 11;
             m.insert(field::user_agent, "test");
             m.body = "*";
-            m.prepare();
+            m.prepare_payload();
             BEAST_EXPECT(str(m) ==
                 "GET / HTTP/1.1\r\n"
                 "User-Agent: test\r\n"
@@ -586,7 +586,7 @@ public:
             m.version = 11;
             m.insert(field::user_agent, "test");
             m.body = "*";
-            m.prepare();
+            m.prepare_payload();
             test::string_ostream ss(ios_);
             error_code ec;
             write(ss, m, ec);