diff --git a/CHANGELOG.md b/CHANGELOG.md
index 3a786148..7cab5e43 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -2,6 +2,7 @@ Version 205
 
 * Doc work
 * Add detail/soft_mutex.hpp
+* Add detail/prng.hpp
 
 --------------------------------------------------------------------------------
 
diff --git a/include/boost/beast/websocket/detail/hybi13.hpp b/include/boost/beast/websocket/detail/hybi13.hpp
index 424a9cc9..30f0ae3c 100644
--- a/include/boost/beast/websocket/detail/hybi13.hpp
+++ b/include/boost/beast/websocket/detail/hybi13.hpp
@@ -36,11 +36,11 @@ inline
 void
 make_sec_ws_key(sec_ws_key_type& key)
 {
-    auto p = stream_prng::prng();
+    auto g = make_prng(true);
     char a[16];
     for(int i = 0; i < 16; i += 4)
     {
-        auto const v = p->secure();
+        auto const v = g();
         a[i  ] =  v        & 0xff;
         a[i+1] = (v >>  8) & 0xff;
         a[i+2] = (v >> 16) & 0xff;
diff --git a/include/boost/beast/websocket/detail/impl/prng.ipp b/include/boost/beast/websocket/detail/impl/prng.ipp
new file mode 100644
index 00000000..b9eb1f6f
--- /dev/null
+++ b/include/boost/beast/websocket/detail/impl/prng.ipp
@@ -0,0 +1,315 @@
+//
+// Copyright (c) 2016-2017 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)
+//
+// Official repository: https://github.com/boostorg/beast
+//
+
+#ifndef BOOST_BEAST_WEBSOCKET_DETAIL_IMPL_PRNG_IPP
+#define BOOST_BEAST_WEBSOCKET_DETAIL_IMPL_PRNG_IPP
+
+#include <boost/beast/core/detail/chacha.hpp>
+#include <boost/align/aligned_alloc.hpp>
+#include <boost/throw_exception.hpp>
+#include <atomic>
+#include <cstdlib>
+#include <mutex>
+#include <new>
+#include <random>
+#include <stdexcept>
+
+namespace boost {
+namespace beast {
+namespace websocket {
+namespace detail {
+
+//------------------------------------------------------------------------------
+
+std::uint32_t const*
+prng_seed(std::seed_seq* ss)
+{
+    struct data
+    {
+        std::uint32_t v[8];
+
+        explicit
+        data(std::seed_seq* pss)
+        {
+            if(! pss)
+            {
+                std::random_device g;
+                std::seed_seq ss{
+                    g(), g(), g(), g(),
+                    g(), g(), g(), g()};
+                ss.generate(v, v+8);
+            }
+            else
+            {
+                pss->generate(v, v+8);
+            }
+        }
+    };
+    static data const d(ss);
+    return d.v;
+}
+
+//------------------------------------------------------------------------------
+
+template<class T>
+class prng_pool
+{
+    std::mutex m_;
+    T* head_ = nullptr;
+
+public:
+    static
+    prng_pool&
+    instance()
+    {
+        static prng_pool p;
+        return p;
+    }
+
+    ~prng_pool()
+    {
+        for(auto p = head_; p;)
+        {
+            auto next = p->next;
+            p->~T();
+            boost::alignment::aligned_free(p);
+            p = next;
+        }
+    }
+
+    prng::ref
+    acquire()
+    {
+        {
+            std::lock_guard<
+                std::mutex> g(m_);
+            if(head_)
+            {
+                auto p = head_;
+                head_ = head_->next;
+                return prng::ref(*p);
+            }
+        }
+        auto p = boost::alignment::aligned_alloc(
+            16, sizeof(T));
+        if(! p)
+            BOOST_THROW_EXCEPTION(std::bad_alloc{});
+        return prng::ref(*(::new(p) T()));
+    }
+
+    void
+    release(T& t)
+    {
+        std::lock_guard<
+            std::mutex> g(m_);
+        t.next = head_;
+        head_ = &t;
+    }
+};
+
+prng::ref
+make_prng_no_tls(bool secure)
+{
+    class fast_prng final : public prng
+    {
+        int refs_ = 0;
+        std::minstd_rand r_;
+
+    public:
+        fast_prng* next;
+
+        fast_prng()
+            : r_([]
+                {
+                    static std::atomic<
+                        std::uint64_t> nonce{0};
+                    auto const pv = prng_seed();
+                    return static_cast<value_type>(
+                        pv[0] + pv[1] + pv[2] + pv[3] +
+                        pv[4] + pv[5] + pv[6] + pv[7] +
+                        ++nonce);
+                }())
+        {
+        }
+
+    protected:
+        prng&
+        acquire() noexcept override
+        {
+            ++refs_;
+            return *this;
+        }
+
+        void
+        release() noexcept override
+        {
+            if(--refs_ == 0)
+                prng_pool<fast_prng>::instance().release(*this);
+        }
+
+        value_type
+        operator()() noexcept override
+        {
+            return r_();
+        }
+    };
+
+    class secure_prng final : public prng
+    {
+        int refs_ = 0;
+        beast::detail::chacha<20> r_;
+
+    public:
+        secure_prng* next;
+
+        secure_prng()
+            : r_(prng_seed(), []
+                {
+                    static std::atomic<
+                        std::uint64_t> nonce{0};
+                    return ++nonce;
+                }())
+        {
+        }
+
+    protected:
+        prng&
+        acquire() noexcept override
+        {
+            ++refs_;
+            return *this;
+        }
+
+        void
+        release() noexcept override
+        {
+            if(--refs_ == 0)
+                prng_pool<secure_prng>::instance().release(*this);
+        }
+
+        value_type
+        operator()() noexcept override
+        {
+            return r_();
+        }
+    };
+
+    if(secure)
+        return prng_pool<secure_prng>::instance().acquire();
+
+    return prng_pool<fast_prng>::instance().acquire();
+}
+
+//------------------------------------------------------------------------------
+
+#if ! BOOST_BEAST_NO_THREAD_LOCAL
+prng::ref
+make_prng_tls(bool secure)
+{
+    class fast_prng final : public prng
+    {
+        std::minstd_rand r_;
+
+    public:
+        fast_prng()
+            : r_([]
+                {
+                    static std::atomic<
+                        std::uint64_t> nonce{0};
+                    auto const pv = prng_seed();
+                    return static_cast<value_type>(
+                        pv[0] + pv[1] + pv[2] + pv[3] +
+                        pv[4] + pv[5] + pv[6] + pv[7] +
+                        ++nonce);
+                }())
+        {
+        }
+
+    protected:
+        prng&
+        acquire() noexcept override
+        {
+            return *this;
+        }
+
+        void
+        release() noexcept override
+        {
+        }
+
+        value_type
+        operator()() noexcept override
+        {
+            return r_();
+        }
+    };
+
+    class secure_prng final : public prng
+    {
+        beast::detail::chacha<20> r_;
+
+    public:
+        secure_prng()
+            : r_(prng_seed(), []
+                {
+                    static std::atomic<
+                        std::uint64_t> nonce{0};
+                    return ++nonce;
+                }())
+        {
+        }
+
+    protected:
+        prng&
+        acquire() noexcept override
+        {
+            return *this;
+        }
+
+        void
+        release() noexcept override
+        {
+        }
+
+        value_type
+        operator()() noexcept override
+        {
+            return r_();
+        }
+    };
+
+    if(secure)
+    {
+        thread_local secure_prng sp;
+        return prng::ref(sp);
+    }
+
+    thread_local fast_prng fp;
+    return prng::ref(fp);
+}
+#endif
+
+//------------------------------------------------------------------------------
+
+prng::ref
+make_prng(bool secure)
+{
+#if BOOST_BEAST_NO_THREAD_LOCAL
+    return make_prng_no_tls(secure);
+#else
+    return make_prng_tls(secure);
+#endif
+}
+
+} // detail
+} // websocket
+} // beast
+} // boost
+
+#endif
diff --git a/include/boost/beast/websocket/detail/prng.hpp b/include/boost/beast/websocket/detail/prng.hpp
new file mode 100644
index 00000000..e34ebb7a
--- /dev/null
+++ b/include/boost/beast/websocket/detail/prng.hpp
@@ -0,0 +1,138 @@
+//
+// Copyright (c) 2016-2017 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)
+//
+// Official repository: https://github.com/boostorg/beast
+//
+
+#ifndef BOOST_BEAST_WEBSOCKET_DETAIL_PRNG_HPP
+#define BOOST_BEAST_WEBSOCKET_DETAIL_PRNG_HPP
+
+#include <boost/beast/core/detail/config.hpp>
+#include <cstdint>
+#include <limits>
+#include <random>
+
+namespace boost {
+namespace beast {
+namespace websocket {
+namespace detail {
+
+// Type-erased UniformRandomBitGenerator
+// with 32-bit unsigned integer value_type
+//
+class prng
+{
+protected:
+    virtual ~prng() = default;
+    virtual prng& acquire() noexcept = 0;
+    virtual void release() noexcept = 0;
+    virtual std::uint32_t operator()() noexcept = 0;
+
+public:
+    using value_type = std::uint32_t;
+
+    class ref
+    {
+        prng& p_;
+
+    public:
+        ref& operator=(ref const&) = delete;
+
+        ~ref()
+        {
+            p_.release();
+        }
+
+        explicit
+        ref(prng& p) noexcept
+            : p_(p.acquire())
+        {
+        }
+
+        ref(ref const& other) noexcept
+            : p_(other.p_.acquire())
+        {
+        }
+
+        value_type
+        operator()() noexcept
+        {
+            return p_();
+        }
+
+        static
+        value_type constexpr
+        min() noexcept
+        {
+            return (std::numeric_limits<
+                value_type>::min)();
+        }
+
+        static
+        value_type constexpr
+        max() noexcept
+        {
+            return (std::numeric_limits<
+                value_type>::max)();
+        }
+    };
+};
+
+//------------------------------------------------------------------------------
+
+// Manually seed the prngs, must be called
+// before acquiring a prng for the first time.
+//
+BOOST_BEAST_DECL
+std::uint32_t const*
+prng_seed(std::seed_seq* ss = nullptr);
+
+// Acquire a PRNG using the no-TLS implementation
+//
+BOOST_BEAST_DECL
+prng::ref
+make_prng_no_tls(bool secure);
+
+// Acquire a PRNG using the TLS implementation
+//
+#if ! BOOST_BEAST_NO_THREAD_LOCAL
+BOOST_BEAST_DECL
+prng::ref
+make_prng_tls(bool secure);
+#endif
+
+// Acquire a PRNG using the TLS implementation if it
+// is available, otherwise using the no-TLS implementation.
+//
+BOOST_BEAST_DECL
+prng::ref
+make_prng(bool secure);
+
+//------------------------------------------------------------------------------
+
+struct stream_prng
+{
+    bool secure_prng_ = true;
+
+    std::uint32_t
+    create_mask()
+    {
+        auto g = make_prng(secure_prng_);
+        for(;;)
+            if(auto key = g())
+                return key;
+    }
+
+};
+
+} // detail
+} // websocket
+} // beast
+} // boost
+
+#include <boost/beast/websocket/detail/impl/prng.ipp>
+
+#endif
diff --git a/include/boost/beast/websocket/detail/stream_base.hpp b/include/boost/beast/websocket/detail/stream_base.hpp
index 95237731..cc2f800d 100644
--- a/include/boost/beast/websocket/detail/stream_base.hpp
+++ b/include/boost/beast/websocket/detail/stream_base.hpp
@@ -15,210 +15,21 @@
 #include <boost/beast/http/string_body.hpp>
 #include <boost/beast/websocket/option.hpp>
 #include <boost/beast/websocket/detail/pmd_extension.hpp>
+#include <boost/beast/websocket/detail/prng.hpp>
 #include <boost/beast/zlib/deflate_stream.hpp>
 #include <boost/beast/zlib/inflate_stream.hpp>
 #include <boost/beast/core/buffers_suffix.hpp>
 #include <boost/beast/core/error.hpp>
-#include <boost/beast/core/detail/chacha.hpp>
 #include <boost/beast/core/detail/clamp.hpp>
-#include <boost/align/aligned_alloc.hpp>
 #include <boost/asio/buffer.hpp>
-#include <boost/core/exchange.hpp>
-#include <atomic>
 #include <cstdint>
 #include <memory>
-#include <new>
-#include <random>
-
-// Turn this on to avoid using thread_local
-//#define BOOST_BEAST_NO_THREAD_LOCAL 1
-
-#ifdef BOOST_BEAST_NO_THREAD_LOCAL
-#include <atomic>
-#include <mutex>
-#endif
 
 namespace boost {
 namespace beast {
 namespace websocket {
 namespace detail {
 
-struct stream_prng
-{
-    bool secure_prng_ = true;
-
-    struct prng_type
-    {
-        std::minstd_rand fast;
-        beast::detail::chacha<20> secure;
-
-#if BOOST_BEAST_NO_THREAD_LOCAL
-        prng_type* next = nullptr;
-#endif
-
-        prng_type(std::uint32_t const* v, std::uint64_t stream)
-            : fast(static_cast<typename decltype(fast)::result_type>(
-                v[0] + v[1] + v[2] + v[3] + v[4] + v[5] + v[6] + v[7] + stream))
-            , secure(v, stream)
-        {
-        }
-    };
-
-    class prng_ref
-    {
-        prng_type* p_;
-
-    public:
-        prng_ref& operator=(prng_ref&&) = delete;
-
-        explicit
-        prng_ref(prng_type& p)
-            : p_(&p)
-        {
-        }
-
-        prng_ref(prng_ref&& other)
-            : p_(boost::exchange(other.p_, nullptr))
-        {
-        }
-
-#ifdef BOOST_BEAST_NO_THREAD_LOCAL
-        ~prng_ref()
-        {
-            if(p_)
-                pool::impl().release(*p_);
-        }
-#endif
-
-        prng_type*
-        operator->() const
-        {
-            return p_;
-        }
-    };
-
-#ifndef BOOST_BEAST_NO_THREAD_LOCAL
-    static
-    prng_ref
-    prng()
-    {
-        static std::atomic<std::uint64_t> stream{0};
-        thread_local prng_type p{seed(), stream++};
-        return prng_ref(p);
-    }
-
-#else
-    static
-    prng_ref
-    prng()
-    {
-        return prng_ref(pool::impl().acquire());
-    }
-
-#endif
-
-    static
-    std::uint32_t const*
-    seed(std::seed_seq* ss = nullptr)
-    {
-        static seed_data d(ss);
-        return d.v;
-    }
-
-    std::uint32_t
-    create_mask()
-    {
-        auto p = prng();
-        if(secure_prng_)
-            for(;;)
-                if(auto key = p->secure())
-                    return key;
-        for(;;)
-            if(auto key = p->fast())
-                return key;
-    }
-
-private:
-    struct seed_data
-    {
-        std::uint32_t v[8];
-
-        explicit
-        seed_data(std::seed_seq* pss)
-        {
-            if(! pss)
-            {
-                std::random_device g;
-                std::seed_seq ss{
-                    g(), g(), g(), g(), g(), g(), g(), g()};
-                ss.generate(v, v+8);
-            }
-            else
-            {
-                pss->generate(v, v+8);
-            }
-        }
-    };
-
-#ifdef BOOST_BEAST_NO_THREAD_LOCAL
-    class pool
-    {
-        prng_type* head_ = nullptr;
-        std::atomic<std::uint64_t> n_{0};
-        std::mutex m_;
-
-    public:
-        ~pool()
-        {
-            for(auto p = head_; p;)
-            {
-                auto next = p->next;
-                p->~prng_type();
-                boost::alignment::aligned_free(p);
-                p = next;
-            }
-        }
-
-        prng_type&
-        acquire()
-        {
-            for(;;)
-            {
-                std::lock_guard<std::mutex> lock(m_);
-                if(! head_)
-                    break;
-                auto p = head_;
-                head_ = head_->next;
-                return *p;
-            }
-            auto p = boost::alignment::aligned_alloc(
-                16, sizeof(prng_type));
-            if(! p)
-                BOOST_THROW_EXCEPTION(std::bad_alloc{});
-            return *(::new(p) prng_type(seed(), n_++));
-        }
-
-        void
-        release(prng_type& p)
-        {
-            std::lock_guard<std::mutex> lock(m_);
-            p.next = head_;
-            head_ = &p;
-        }
-
-        static
-        pool&
-        impl()
-        {
-            static pool instance;
-            return instance;
-        }
-    };
-#endif
-};
-
-//------------------------------------------------------------------------------
-
 template<bool deflateSupported>
 struct stream_base : stream_prng
 {
diff --git a/include/boost/beast/websocket/stream.hpp b/include/boost/beast/websocket/stream.hpp
index beca0e96..03e9ecd1 100644
--- a/include/boost/beast/websocket/stream.hpp
+++ b/include/boost/beast/websocket/stream.hpp
@@ -3511,7 +3511,7 @@ inline
 void
 seed_prng(std::seed_seq& ss)
 {
-    detail::stream_prng::seed(&ss);
+    detail::prng_seed(&ss);
 }
 
 } // websocket
diff --git a/test/beast/websocket/CMakeLists.txt b/test/beast/websocket/CMakeLists.txt
index 432b7b76..20ed3d4f 100644
--- a/test/beast/websocket/CMakeLists.txt
+++ b/test/beast/websocket/CMakeLists.txt
@@ -17,6 +17,7 @@ add_executable (tests-beast-websocket
     ${TEST_MAIN}
     Jamfile
     test.hpp
+    _detail_prng.cpp
     accept.cpp
     close.cpp
     error.cpp
diff --git a/test/beast/websocket/Jamfile b/test/beast/websocket/Jamfile
index 4cdfcb68..7c5e5449 100644
--- a/test/beast/websocket/Jamfile
+++ b/test/beast/websocket/Jamfile
@@ -8,6 +8,7 @@
 #
 
 local SOURCES =
+    _detail_prng.cpp
     accept.cpp
     close.cpp
     error.cpp
diff --git a/test/beast/websocket/_detail_prng.cpp b/test/beast/websocket/_detail_prng.cpp
new file mode 100644
index 00000000..b1bfa052
--- /dev/null
+++ b/test/beast/websocket/_detail_prng.cpp
@@ -0,0 +1,69 @@
+//
+// Copyright (w) 2016-2017 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)
+//
+// Official repository: https://github.com/boostorg/beast
+//
+
+// Test that header file is self-contained.
+#include <boost/beast/websocket/detail/prng.hpp>
+
+#include <boost/beast/_experimental/unit_test/suite.hpp>
+
+namespace boost {
+namespace beast {
+namespace websocket {
+namespace detail {
+
+class prng_test
+    : public beast::unit_test::suite
+{
+public:
+#if 0
+    char const* name() const noexcept //override
+    {
+        return "boost.beast.websocket.detail.prng";
+    }
+#endif
+
+    template <class F>
+    void
+    testPrng(F const& f)
+    {
+        {
+            auto v = f()();
+            BEAST_EXPECT(
+                v >= (prng::ref::min)() &&
+                v <= (prng::ref::max)());
+        }
+        {
+            auto v = f()();
+            BEAST_EXPECT(
+                v >= (prng::ref::min)() &&
+                v <= (prng::ref::max)());
+        }
+    }
+
+    void
+    run() override
+    {
+        testPrng([]{ return make_prng(true); });
+        testPrng([]{ return make_prng(false); });
+        testPrng([]{ return make_prng_no_tls(true); });
+        testPrng([]{ return make_prng_no_tls(false); });
+    #if ! BOOST_BEAST_NO_THREAD_LOCAL
+        testPrng([]{ return make_prng_tls(true); });
+        testPrng([]{ return make_prng_tls(false); });
+    #endif
+    }
+};
+
+//static prng_test t;
+BEAST_DEFINE_TESTSUITE(beast,websocket,prng);
+
+} // detail
+} // websocket
+} // beast
+} // boost