diff --git a/include/beast/core/detail/clamp.hpp b/include/beast/core/detail/clamp.hpp
new file mode 100644
index 00000000..3a72f3a0
--- /dev/null
+++ b/include/beast/core/detail/clamp.hpp
@@ -0,0 +1,40 @@
+//
+// Copyright (c) 2013-2016 Vinnie Falco (vinnie dot falco at gmail dot com)
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+
+#ifndef BEAST_CORE_DETAIL_CLAMP_HPP
+#define BEAST_CORE_DETAIL_CLAMP_HPP
+
+#include <limits>
+#include <cstdlib>
+
+namespace beast {
+namespace detail {
+
+template<class UInt>
+static
+std::size_t
+clamp(UInt x)
+{
+    if(x >= std::numeric_limits<std::size_t>::max())
+        return std::numeric_limits<std::size_t>::max();
+    return static_cast<std::size_t>(x);
+}
+
+template<class UInt>
+static
+std::size_t
+clamp(UInt x, std::size_t limit)
+{
+    if(x >= limit)
+        return limit;
+    return static_cast<std::size_t>(x);
+}
+
+} // detail
+} // beast
+
+#endif
diff --git a/include/beast/websocket/detail/stream_base.hpp b/include/beast/websocket/detail/stream_base.hpp
index 08579a0f..ec1c7fba 100644
--- a/include/beast/websocket/detail/stream_base.hpp
+++ b/include/beast/websocket/detail/stream_base.hpp
@@ -9,6 +9,7 @@
 #define BEAST_WEBSOCKET_DETAIL_STREAM_BASE_HPP
 
 #include <beast/websocket/error.hpp>
+#include <beast/websocket/option.hpp>
 #include <beast/websocket/rfc6455.hpp>
 #include <beast/websocket/detail/decorator.hpp>
 #include <beast/websocket/detail/frame.hpp>
@@ -21,36 +22,12 @@
 #include <boost/asio/error.hpp>
 #include <boost/assert.hpp>
 #include <cstdint>
-#include <functional>
-#include <limits>
 #include <memory>
 
 namespace beast {
 namespace websocket {
 namespace detail {
 
-template<class UInt>
-static
-std::size_t
-clamp(UInt x)
-{
-    if(x >= std::numeric_limits<std::size_t>::max())
-        return std::numeric_limits<std::size_t>::max();
-    return static_cast<std::size_t>(x);
-}
-
-template<class UInt>
-static
-std::size_t
-clamp(UInt x, std::size_t limit)
-{
-    if(x >= limit)
-        return limit;
-    return static_cast<std::size_t>(x);
-}
-
-using pong_cb = std::function<void(ping_data const&)>;
-
 /// Identifies the role of a WebSockets stream.
 enum class role_type
 {
diff --git a/include/beast/websocket/impl/read.ipp b/include/beast/websocket/impl/read.ipp
index d4acfee5..0b2feeb5 100644
--- a/include/beast/websocket/impl/read.ipp
+++ b/include/beast/websocket/impl/read.ipp
@@ -14,6 +14,7 @@
 #include <beast/core/prepare_buffers.hpp>
 #include <beast/core/static_streambuf.hpp>
 #include <beast/core/stream_concepts.hpp>
+#include <beast/core/detail/clamp.hpp>
 #include <boost/assert.hpp>
 #include <boost/optional.hpp>
 #include <memory>
@@ -148,6 +149,7 @@ void
 stream<NextLayer>::read_frame_op<DynamicBuffer, Handler>::
 operator()(error_code ec,std::size_t bytes_transferred, bool again)
 {
+    using beast::detail::clamp;
     enum
     {
         do_start = 0,
@@ -191,8 +193,7 @@ operator()(error_code ec,std::size_t bytes_transferred, bool again)
 
             case do_read_payload:
                 d.state = do_read_payload + 1;
-                d.dmb = d.db.prepare(
-                    detail::clamp(d.ws.rd_need_));
+                d.dmb = d.db.prepare(clamp(d.ws.rd_need_));
                 // receive payload data
                 d.ws.stream_.async_read_some(
                     *d.dmb, std::move(*this));
@@ -590,6 +591,7 @@ read_frame(frame_info& fi, DynamicBuffer& dynabuf, error_code& ec)
         "SyncStream requirements not met");
     static_assert(beast::is_DynamicBuffer<DynamicBuffer>::value,
         "DynamicBuffer requirements not met");
+    using beast::detail::clamp;
     close_code::value code{};
     for(;;)
     {
@@ -668,8 +670,7 @@ read_frame(frame_info& fi, DynamicBuffer& dynabuf, error_code& ec)
             }
         }
         // read payload
-        auto smb = dynabuf.prepare(
-            detail::clamp(rd_need_));
+        auto smb = dynabuf.prepare(clamp(rd_need_));
         auto const bytes_transferred =
             stream_.read_some(smb, ec);
         failed_ = ec != 0;
diff --git a/include/beast/websocket/impl/write.ipp b/include/beast/websocket/impl/write.ipp
index 28d2aec3..d1cffa05 100644
--- a/include/beast/websocket/impl/write.ipp
+++ b/include/beast/websocket/impl/write.ipp
@@ -16,6 +16,7 @@
 #include <beast/core/prepare_buffers.hpp>
 #include <beast/core/static_streambuf.hpp>
 #include <beast/core/stream_concepts.hpp>
+#include <beast/core/detail/clamp.hpp>
 #include <beast/websocket/detail/frame.hpp>
 #include <boost/assert.hpp>
 #include <algorithm>
@@ -122,6 +123,7 @@ class stream<NextLayer>::write_frame_op
             , cont(boost_asio_handler_cont_helpers::
                 is_continuation(h))
         {
+            using beast::detail::clamp;
             fh.op = ws.wr_.cont ?
                 opcode::cont : ws.wr_opcode_;
             ws.wr_.cont = ! fin;
@@ -135,8 +137,7 @@ class stream<NextLayer>::write_frame_op
             {
                 fh.key = ws.maskgen_();
                 detail::prepare_key(key, fh.key);
-                tmp_size = detail::clamp(
-                    fh.len, ws.wr_buf_size_);
+                tmp_size = clamp(fh.len, ws.wr_buf_size_);
                 tmp = boost_asio_handler_alloc_helpers::
                     allocate(tmp_size, h);
                 remain = fh.len;
@@ -232,6 +233,7 @@ stream<NextLayer>::
 write_frame_op<Buffers, Handler>::
 operator()(error_code ec, bool again)
 {
+    using beast::detail::clamp;
     using boost::asio::buffer_copy;
     using boost::asio::mutable_buffers_1;
     auto& d = *d_;
@@ -275,8 +277,7 @@ operator()(error_code ec, bool again)
                         std::move(*this));
                 return;
             }
-            auto const n =
-                detail::clamp(d.remain, d.tmp_size);
+            auto const n = clamp(d.remain, d.tmp_size);
             mutable_buffers_1 mb{d.tmp, n};
             buffer_copy(mb, d.cb);
             d.cb.consume(n);
@@ -295,8 +296,7 @@ operator()(error_code ec, bool again)
         // sent masked payload
         case 2:
         {
-            auto const n =
-                detail::clamp(d.remain, d.tmp_size);
+            auto const n = clamp(d.remain, d.tmp_size);
             mutable_buffers_1 mb{d.tmp,
                 static_cast<std::size_t>(n)};
             buffer_copy(mb, d.cb);
@@ -396,6 +396,7 @@ write_frame(bool fin,
     static_assert(beast::is_ConstBufferSequence<
         ConstBufferSequence>::value,
             "ConstBufferSequence requirements not met");
+    using beast::detail::clamp;
     using boost::asio::buffer;
     using boost::asio::buffer_copy;
     using boost::asio::buffer_size;
@@ -434,8 +435,7 @@ write_frame(bool fin,
             ConstBufferSequence> cb(buffers);
         for(;;)
         {
-            auto const n =
-                detail::clamp(remain, wr_.size);
+            auto const n = clamp(remain, wr_.size);
             fh.len = n;
             remain -= n;
             fh.fin = fin ? remain == 0 : false;
@@ -466,7 +466,7 @@ write_frame(bool fin,
         consuming_buffers<
             ConstBufferSequence> cb(buffers);
         {
-            auto const n = detail::clamp(remain, wr_.size);
+            auto const n = clamp(remain, wr_.size);
             auto const mb = buffer(wr_.buf.get(), n);
             buffer_copy(mb, cb);
             cb.consume(n);
@@ -480,7 +480,7 @@ write_frame(bool fin,
         }
         while(remain > 0)
         {
-            auto const n = detail::clamp(remain, wr_.size);
+            auto const n = clamp(remain, wr_.size);
             auto const mb = buffer(wr_.buf.get(), n);
             buffer_copy(mb, cb);
             cb.consume(n);
@@ -503,8 +503,7 @@ write_frame(bool fin,
             fh.key = maskgen_();
             detail::prepared_key_type key;
             detail::prepare_key(key, fh.key);
-            auto const n =
-                detail::clamp(remain, wr_.size);
+            auto const n = clamp(remain, wr_.size);
             auto const mb = buffer(wr_.buf.get(), n);
             buffer_copy(mb, cb);
             detail::mask_inplace(mb, key);
diff --git a/include/beast/websocket/option.hpp b/include/beast/websocket/option.hpp
index 818a74f3..127aa158 100644
--- a/include/beast/websocket/option.hpp
+++ b/include/beast/websocket/option.hpp
@@ -9,9 +9,10 @@
 #define BEAST_WEBSOCKET_OPTION_HPP
 
 #include <beast/websocket/rfc6455.hpp>
-#include <beast/websocket/detail/stream_base.hpp>
+#include <beast/websocket/detail/decorator.hpp>
 #include <algorithm>
 #include <cstdint>
+#include <functional>
 #include <stdexcept>
 #include <type_traits>
 #include <utility>
@@ -191,6 +192,12 @@ struct message_type
 };
 #endif
 
+namespace detail {
+
+using pong_cb = std::function<void(ping_data const&)>;
+
+} // detail
+
 /** Pong callback option.
 
     Sets the callback to be invoked whenever a pong is received
diff --git a/test/Jamfile b/test/Jamfile
index a01bda0f..41ba85e2 100644
--- a/test/Jamfile
+++ b/test/Jamfile
@@ -20,6 +20,7 @@ unit-test core-tests :
     core/buffer_cat.cpp
     core/buffer_concepts.cpp
     core/buffers_adapter.cpp
+    core/clamp.cpp
     core/consuming_buffers.cpp
     core/dynabuf_readstream.cpp
     core/error.cpp
@@ -78,7 +79,6 @@ unit-test websocket-tests :
     websocket/teardown.cpp
     websocket/frame.cpp
     websocket/mask.cpp
-    websocket/stream_base.cpp
     websocket/utf8_checker.cpp
     ;
 
diff --git a/test/core/CMakeLists.txt b/test/core/CMakeLists.txt
index e6d291cd..8f452ad2 100644
--- a/test/core/CMakeLists.txt
+++ b/test/core/CMakeLists.txt
@@ -15,6 +15,7 @@ add_executable (core-tests
     buffer_cat.cpp
     buffer_concepts.cpp
     buffers_adapter.cpp
+    clamp.cpp
     consuming_buffers.cpp
     dynabuf_readstream.cpp
     error.cpp
diff --git a/test/websocket/stream_base.cpp b/test/core/clamp.cpp
similarity index 70%
rename from test/websocket/stream_base.cpp
rename to test/core/clamp.cpp
index 4bba083e..a429f7f9 100644
--- a/test/websocket/stream_base.cpp
+++ b/test/core/clamp.cpp
@@ -6,22 +6,20 @@
 //
 
 // Test that header file is self-contained.
-#include <beast/websocket/detail/stream_base.hpp>
+#include <beast/core/detail/clamp.hpp>
 
 #include <beast/unit_test/suite.hpp>
-#include <initializer_list>
 #include <climits>
 
 namespace beast {
-namespace websocket {
 namespace detail {
 
-class stream_base_test : public beast::unit_test::suite
+class clamp_test : public beast::unit_test::suite
 {
 public:
     void testClamp()
     {
-        BEAST_EXPECT(detail::clamp(
+        BEAST_EXPECT(clamp(
             std::numeric_limits<std::uint64_t>::max()) ==
                 std::numeric_limits<std::size_t>::max());
     }
@@ -32,9 +30,8 @@ public:
     }
 };
 
-BEAST_DEFINE_TESTSUITE(stream_base,websocket,beast);
+BEAST_DEFINE_TESTSUITE(clamp,core,beast);
 
 } // detail
-} // websocket
 } // beast
 
diff --git a/test/websocket/CMakeLists.txt b/test/websocket/CMakeLists.txt
index 51741891..9de18db9 100644
--- a/test/websocket/CMakeLists.txt
+++ b/test/websocket/CMakeLists.txt
@@ -17,7 +17,6 @@ add_executable (websocket-tests
     teardown.cpp
     frame.cpp
     mask.cpp
-    stream_base.cpp
     utf8_checker.cpp
 )