diff --git a/example/https-client/https_client.cpp b/example/https-client/https_client.cpp
index b64adc6..cde4932 100644
--- a/example/https-client/https_client.cpp
+++ b/example/https-client/https_client.cpp
@@ -63,8 +63,14 @@ run_client(
     // Connect to the server (throws on error)
     (co_await s.connect(corosio::endpoint(addr, port))).value();
 
+    // Configure TLS context
+    corosio::tls::context ctx;
+    ctx.set_hostname(hostname);
+    ctx.set_default_verify_paths().value();
+    ctx.set_verify_mode(corosio::tls::verify_mode::peer).value();
+
     // Wrap socket in TLS stream
-    corosio::wolfssl_stream secure(s);
+    corosio::wolfssl_stream secure(s, ctx);
 
     // Perform TLS handshake
     (co_await secure.handshake(corosio::wolfssl_stream::client)).value();
diff --git a/include/boost/corosio/signal_set.hpp b/include/boost/corosio/signal_set.hpp
index a4a3b9b..fbf1413 100644
--- a/include/boost/corosio/signal_set.hpp
+++ b/include/boost/corosio/signal_set.hpp
@@ -20,7 +20,9 @@
 #include <boost/capy/concept/io_awaitable.hpp>
 #include <boost/capy/concept/executor.hpp>
 #include <boost/system/error_code.hpp>
+#include <boost/system/result.hpp>
 
+#include <concepts>
 #include <coroutine>
 #include <stop_token>
 
@@ -73,15 +75,6 @@ class BOOST_COROSIO_DECL signal_set : public io_object
             return {ec_, signal_number_};
         }
 
-        template<typename Ex>
-        auto await_suspend(
-            std::coroutine_handle<> h,
-            Ex const& ex) -> std::coroutine_handle<>
-        {
-            s_.get().wait(h, ex, token_, &ec_, &signal_number_);
-            return std::noop_coroutine();
-        }
-
         template<typename Ex>
         auto await_suspend(
             std::coroutine_handle<> h,
@@ -104,61 +97,42 @@ class BOOST_COROSIO_DECL signal_set : public io_object
             system::error_code*,
             int*) = 0;
 
-        virtual system::error_code add(int signal_number) = 0;
-        virtual system::error_code remove(int signal_number) = 0;
-        virtual system::error_code clear() = 0;
+        virtual system::result<void> add(int signal_number) = 0;
+        virtual system::result<void> remove(int signal_number) = 0;
+        virtual system::result<void> clear() = 0;
         virtual void cancel() = 0;
     };
 
-public:
     /** Destructor.
 
         Cancels any pending operations and releases signal resources.
     */
     ~signal_set();
 
-    /** Construct a signal set without adding any signals.
+    /** Construct an empty signal set.
 
         @param ctx The execution context that will own this signal set.
     */
     explicit signal_set(capy::execution_context& ctx);
 
-    /** Construct a signal set and add one signal.
-
-        @param ctx The execution context that will own this signal set.
-        @param signal_number_1 The signal number to be added.
-
-        @throws boost::system::system_error Thrown on failure.
-    */
-    signal_set(capy::execution_context& ctx, int signal_number_1);
-
-    /** Construct a signal set and add two signals.
+    /** Construct a signal set with initial signals.
 
         @param ctx The execution context that will own this signal set.
-        @param signal_number_1 The first signal number to be added.
-        @param signal_number_2 The second signal number to be added.
+        @param signal First signal number to add.
+        @param signals Additional signal numbers to add.
 
         @throws boost::system::system_error Thrown on failure.
     */
+    template<std::convertible_to<int>... Signals>
     signal_set(
         capy::execution_context& ctx,
-        int signal_number_1,
-        int signal_number_2);
-
-    /** Construct a signal set and add three signals.
-
-        @param ctx The execution context that will own this signal set.
-        @param signal_number_1 The first signal number to be added.
-        @param signal_number_2 The second signal number to be added.
-        @param signal_number_3 The third signal number to be added.
-
-        @throws boost::system::system_error Thrown on failure.
-    */
-    signal_set(
-        capy::execution_context& ctx,
-        int signal_number_1,
-        int signal_number_2,
-        int signal_number_3);
+        int signal,
+        Signals... signals)
+        : signal_set(ctx)
+    {
+        add(signal).value();
+        (add(signals).value(), ...);
+    }
 
     /** Move constructor.
 
@@ -192,19 +166,9 @@ class BOOST_COROSIO_DECL signal_set : public io_object
 
         @param signal_number The signal to be added to the set.
 
-        @throws boost::system::system_error Thrown on failure.
+        @return Success, or an error if the signal could not be added.
     */
-    void add(int signal_number);
-
-    /** Add a signal to the signal set.
-
-        This function adds the specified signal to the set. It has no
-        effect if the signal is already in the set.
-
-        @param signal_number The signal to be added to the set.
-        @param ec Set to indicate what error occurred, if any.
-    */
-    void add(int signal_number, system::error_code& ec);
+    system::result<void> add(int signal_number);
 
     /** Remove a signal from the signal set.
 
@@ -213,37 +177,18 @@ class BOOST_COROSIO_DECL signal_set : public io_object
 
         @param signal_number The signal to be removed from the set.
 
-        @throws boost::system::system_error Thrown on failure.
-    */
-    void remove(int signal_number);
-
-    /** Remove a signal from the signal set.
-
-        This function removes the specified signal from the set. It has
-        no effect if the signal is not in the set.
-
-        @param signal_number The signal to be removed from the set.
-        @param ec Set to indicate what error occurred, if any.
-    */
-    void remove(int signal_number, system::error_code& ec);
-
-    /** Remove all signals from the signal set.
-
-        This function removes all signals from the set. It has no effect
-        if the set is already empty.
-
-        @throws boost::system::system_error Thrown on failure.
+        @return Success, or an error if the signal could not be removed.
     */
-    void clear();
+    system::result<void> remove(int signal_number);
 
     /** Remove all signals from the signal set.
 
         This function removes all signals from the set. It has no effect
         if the set is already empty.
 
-        @param ec Set to indicate what error occurred, if any.
+        @return Success, or an error if resetting any signal handler fails.
     */
-    void clear(system::error_code& ec);
+    system::result<void> clear();
 
     /** Cancel all operations associated with the signal set.
 
diff --git a/src/corosio/src/detail/posix/signals.cpp b/src/corosio/src/detail/posix/signals.cpp
index 59bcb6a..8a4d853 100644
--- a/src/corosio/src/detail/posix/signals.cpp
+++ b/src/corosio/src/detail/posix/signals.cpp
@@ -16,9 +16,6 @@
 
 #include <boost/corosio/detail/except.hpp>
 #include <boost/capy/error.hpp>
-#include <boost/capy/ex/any_coro.hpp>
-
-#include <cerrno>
 #include <mutex>
 
 #include <signal.h>
@@ -78,7 +75,7 @@ operator()()
     auto* service = svc;
     svc = nullptr;
 
-    d.post(capy::any_coro{h});
+    d.post(h);
 
     // Balance the on_work_started() from start_wait
     if (service)
@@ -134,28 +131,28 @@ wait(
             *ec = make_error_code(capy::error::canceled);
         if (signal_out)
             *signal_out = 0;
-        d.post(capy::any_coro{h});
+        d.post(h);
         return;
     }
 
     svc_.start_wait(*this, &pending_op_);
 }
 
-system::error_code
+system::result<void>
 posix_signal_impl::
 add(int signal_number)
 {
     return svc_.add_signal(*this, signal_number);
 }
 
-system::error_code
+system::result<void>
 posix_signal_impl::
 remove(int signal_number)
 {
     return svc_.remove_signal(*this, signal_number);
 }
 
-system::error_code
+system::result<void>
 posix_signal_impl::
 clear()
 {
@@ -237,13 +234,13 @@ destroy_impl(posix_signal_impl& impl)
     delete &impl;
 }
 
-system::error_code
+system::result<void>
 posix_signals::
 add_signal(
     posix_signal_impl& impl,
     int signal_number)
 {
-    if (signal_number < 1 || signal_number >= max_signal_number)
+    if (signal_number < 0 || signal_number >= max_signal_number)
         return make_error_code(system::errc::invalid_argument);
 
     signal_state* state = get_signal_state();
@@ -292,13 +289,13 @@ add_signal(
     return {};
 }
 
-system::error_code
+system::result<void>
 posix_signals::
 remove_signal(
     posix_signal_impl& impl,
     int signal_number)
 {
-    if (signal_number < 1 || signal_number >= max_signal_number)
+    if (signal_number < 0 || signal_number >= max_signal_number)
         return make_error_code(system::errc::invalid_argument);
 
     signal_state* state = get_signal_state();
@@ -318,7 +315,10 @@ remove_signal(
 
     // Restore default handler on last global unregistration
     if (state->registration_count[signal_number] == 1)
-        ::signal(signal_number, SIG_DFL);
+    {
+        if (::signal(signal_number, SIG_DFL) == SIG_ERR)
+            return make_error_code(system::errc::invalid_argument);
+    }
 
     *deletion_point = reg->next_in_set;
 
@@ -336,7 +336,7 @@ remove_signal(
     return {};
 }
 
-system::error_code
+system::result<void>
 posix_signals::
 clear_signals(posix_signal_impl& impl)
 {
@@ -344,12 +344,17 @@ clear_signals(posix_signal_impl& impl)
     std::lock_guard state_lock(state->mutex);
     std::lock_guard lock(mutex_);
 
+    system::error_code first_error;
+
     while (signal_registration* reg = impl.signals_)
     {
         int signal_number = reg->signal_number;
 
         if (state->registration_count[signal_number] == 1)
-            ::signal(signal_number, SIG_DFL);
+        {
+            if (::signal(signal_number, SIG_DFL) == SIG_ERR && !first_error)
+                first_error = make_error_code(system::errc::invalid_argument);
+        }
 
         impl.signals_ = reg->next_in_set;
 
@@ -366,6 +371,8 @@ clear_signals(posix_signal_impl& impl)
         delete reg;
     }
 
+    if (first_error)
+        return first_error;
     return {};
 }
 
@@ -392,7 +399,7 @@ cancel_wait(posix_signal_impl& impl)
             *op->ec_out = make_error_code(capy::error::canceled);
         if (op->signal_out)
             *op->signal_out = 0;
-        op->d.post(capy::any_coro{op->h});
+        op->d.post(op->h);
         sched_.on_work_finished();
     }
 }
@@ -430,7 +437,7 @@ void
 posix_signals::
 deliver_signal(int signal_number)
 {
-    if (signal_number < 1 || signal_number >= max_signal_number)
+    if (signal_number < 0 || signal_number >= max_signal_number)
         return;
 
     signal_state* state = get_signal_state();
@@ -541,40 +548,6 @@ signal_set(capy::execution_context& ctx)
     impl_ = &ctx.use_service<detail::posix_signals>().create_impl();
 }
 
-signal_set::
-signal_set(capy::execution_context& ctx, int signal_number_1)
-    : io_object(ctx)
-{
-    impl_ = &ctx.use_service<detail::posix_signals>().create_impl();
-    add(signal_number_1);
-}
-
-signal_set::
-signal_set(
-    capy::execution_context& ctx,
-    int signal_number_1,
-    int signal_number_2)
-    : io_object(ctx)
-{
-    impl_ = &ctx.use_service<detail::posix_signals>().create_impl();
-    add(signal_number_1);
-    add(signal_number_2);
-}
-
-signal_set::
-signal_set(
-    capy::execution_context& ctx,
-    int signal_number_1,
-    int signal_number_2,
-    int signal_number_3)
-    : io_object(ctx)
-{
-    impl_ = &ctx.use_service<detail::posix_signals>().create_impl();
-    add(signal_number_1);
-    add(signal_number_2);
-    add(signal_number_3);
-}
-
 signal_set::
 signal_set(signal_set&& other) noexcept
     : io_object(std::move(other))
@@ -601,52 +574,25 @@ operator=(signal_set&& other)
     return *this;
 }
 
-void
+system::result<void>
 signal_set::
 add(int signal_number)
 {
-    system::error_code ec = get().add(signal_number);
-    if (ec)
-        detail::throw_system_error(ec, "signal_set::add");
+    return get().add(signal_number);
 }
 
-void
-signal_set::
-add(int signal_number, system::error_code& ec)
-{
-    ec = get().add(signal_number);
-}
-
-void
+system::result<void>
 signal_set::
 remove(int signal_number)
 {
-    system::error_code ec = get().remove(signal_number);
-    if (ec)
-        detail::throw_system_error(ec, "signal_set::remove");
+    return get().remove(signal_number);
 }
 
-void
-signal_set::
-remove(int signal_number, system::error_code& ec)
-{
-    ec = get().remove(signal_number);
-}
-
-void
+system::result<void>
 signal_set::
 clear()
 {
-    system::error_code ec = get().clear();
-    if (ec)
-        detail::throw_system_error(ec, "signal_set::clear");
-}
-
-void
-signal_set::
-clear(system::error_code& ec)
-{
-    ec = get().clear();
+    return get().clear();
 }
 
 void
diff --git a/src/corosio/src/detail/posix/signals.hpp b/src/corosio/src/detail/posix/signals.hpp
index 93b599f..3e60f7f 100644
--- a/src/corosio/src/detail/posix/signals.hpp
+++ b/src/corosio/src/detail/posix/signals.hpp
@@ -16,10 +16,12 @@
 
 #include <boost/corosio/detail/config.hpp>
 #include <boost/corosio/signal_set.hpp>
+#include <boost/capy/ex/any_coro.hpp>
 #include <boost/capy/ex/any_executor_ref.hpp>
 #include <boost/capy/ex/execution_context.hpp>
 #include <boost/capy/core/intrusive_list.hpp>
 #include <boost/system/error_code.hpp>
+#include <boost/system/result.hpp>
 
 #include "src/detail/scheduler_op.hpp"
 
@@ -46,7 +48,7 @@ enum { max_signal_number = 64 };
 /** Signal wait operation state. */
 struct signal_op : scheduler_op
 {
-    std::coroutine_handle<> h;
+    capy::any_coro h;
     capy::any_executor_ref d;
     system::error_code* ec_out = nullptr;
     int* signal_out = nullptr;
@@ -102,9 +104,9 @@ class posix_signal_impl
         system::error_code*,
         int*) override;
 
-    system::error_code add(int signal_number) override;
-    system::error_code remove(int signal_number) override;
-    system::error_code clear() override;
+    system::result<void> add(int signal_number) override;
+    system::result<void> remove(int signal_number) override;
+    system::result<void> clear() override;
     void cancel() override;
 };
 
@@ -153,9 +155,9 @@ class posix_signals : public capy::execution_context::service
 
         @param impl The signal implementation to modify.
         @param signal_number The signal to register.
-        @return Error code, or success.
+        @return Success, or an error.
     */
-    system::error_code add_signal(
+    system::result<void> add_signal(
         posix_signal_impl& impl,
         int signal_number);
 
@@ -163,18 +165,18 @@ class posix_signals : public capy::execution_context::service
 
         @param impl The signal implementation to modify.
         @param signal_number The signal to unregister.
-        @return Error code, or success.
+        @return Success, or an error.
     */
-    system::error_code remove_signal(
+    system::result<void> remove_signal(
         posix_signal_impl& impl,
         int signal_number);
 
     /** Remove all signals from a signal set.
 
         @param impl The signal implementation to clear.
-        @return Error code, or success.
+        @return Success, or an error.
     */
-    system::error_code clear_signals(posix_signal_impl& impl);
+    system::result<void> clear_signals(posix_signal_impl& impl);
 
     /** Cancel pending wait operations.
 
diff --git a/src/corosio/src/detail/win/signals.cpp b/src/corosio/src/detail/win/signals.cpp
index 377e36c..a58e217 100644
--- a/src/corosio/src/detail/win/signals.cpp
+++ b/src/corosio/src/detail/win/signals.cpp
@@ -215,21 +215,21 @@ wait(
     svc_.start_wait(*this, &pending_op_);
 }
 
-system::error_code
+system::result<void>
 win_signal_impl::
 add(int signal_number)
 {
     return svc_.add_signal(*this, signal_number);
 }
 
-system::error_code
+system::result<void>
 win_signal_impl::
 remove(int signal_number)
 {
     return svc_.remove_signal(*this, signal_number);
 }
 
-system::error_code
+system::result<void>
 win_signal_impl::
 clear()
 {
@@ -310,7 +310,7 @@ destroy_impl(win_signal_impl& impl)
     delete &impl;
 }
 
-system::error_code
+system::result<void>
 win_signals::
 add_signal(
     win_signal_impl& impl,
@@ -367,7 +367,7 @@ add_signal(
     return {};
 }
 
-system::error_code
+system::result<void>
 win_signals::
 remove_signal(
     win_signal_impl& impl,
@@ -416,7 +416,7 @@ remove_signal(
     return {};
 }
 
-system::error_code
+system::result<void>
 win_signals::
 clear_signals(win_signal_impl& impl)
 {
@@ -424,13 +424,18 @@ clear_signals(win_signal_impl& impl)
     std::lock_guard<std::mutex> state_lock(state->mutex);
     std::lock_guard<win_mutex> lock(mutex_);
 
+    system::error_code first_error;
+
     while (signal_registration* reg = impl.signals_)
     {
         int signal_number = reg->signal_number;
 
         // Restore default handler if last registration
         if (state->registration_count[signal_number] == 1)
-            ::signal(signal_number, SIG_DFL);
+        {
+            if (::signal(signal_number, SIG_DFL) == SIG_ERR && !first_error)
+                first_error = make_error_code(system::errc::invalid_argument);
+        }
 
         // Remove from set's list
         impl.signals_ = reg->next_in_set;
@@ -448,6 +453,8 @@ clear_signals(win_signal_impl& impl)
         delete reg;
     }
 
+    if (first_error)
+        return first_error;
     return {};
 }
 
@@ -633,40 +640,6 @@ signal_set(capy::execution_context& ctx)
     impl_ = &ctx.use_service<detail::win_signals>().create_impl();
 }
 
-signal_set::
-signal_set(capy::execution_context& ctx, int signal_number_1)
-    : io_object(ctx)
-{
-    impl_ = &ctx.use_service<detail::win_signals>().create_impl();
-    add(signal_number_1);
-}
-
-signal_set::
-signal_set(
-    capy::execution_context& ctx,
-    int signal_number_1,
-    int signal_number_2)
-    : io_object(ctx)
-{
-    impl_ = &ctx.use_service<detail::win_signals>().create_impl();
-    add(signal_number_1);
-    add(signal_number_2);
-}
-
-signal_set::
-signal_set(
-    capy::execution_context& ctx,
-    int signal_number_1,
-    int signal_number_2,
-    int signal_number_3)
-    : io_object(ctx)
-{
-    impl_ = &ctx.use_service<detail::win_signals>().create_impl();
-    add(signal_number_1);
-    add(signal_number_2);
-    add(signal_number_3);
-}
-
 signal_set::
 signal_set(signal_set&& other) noexcept
     : io_object(std::move(other))
@@ -693,52 +666,25 @@ operator=(signal_set&& other)
     return *this;
 }
 
-void
+system::result<void>
 signal_set::
 add(int signal_number)
 {
-    system::error_code ec = get().add(signal_number);
-    if (ec)
-        detail::throw_system_error(ec, "signal_set::add");
-}
-
-void
-signal_set::
-add(int signal_number, system::error_code& ec)
-{
-    ec = get().add(signal_number);
+    return get().add(signal_number);
 }
 
-void
+system::result<void>
 signal_set::
 remove(int signal_number)
 {
-    system::error_code ec = get().remove(signal_number);
-    if (ec)
-        detail::throw_system_error(ec, "signal_set::remove");
+    return get().remove(signal_number);
 }
 
-void
-signal_set::
-remove(int signal_number, system::error_code& ec)
-{
-    ec = get().remove(signal_number);
-}
-
-void
+system::result<void>
 signal_set::
 clear()
 {
-    system::error_code ec = get().clear();
-    if (ec)
-        detail::throw_system_error(ec, "signal_set::clear");
-}
-
-void
-signal_set::
-clear(system::error_code& ec)
-{
-    ec = get().clear();
+    return get().clear();
 }
 
 void
diff --git a/src/corosio/src/detail/win/signals.hpp b/src/corosio/src/detail/win/signals.hpp
index 6803bec..e163982 100644
--- a/src/corosio/src/detail/win/signals.hpp
+++ b/src/corosio/src/detail/win/signals.hpp
@@ -22,6 +22,7 @@
 #include <boost/capy/core/intrusive_list.hpp>
 #include <boost/capy/core/intrusive_queue.hpp>
 #include <boost/system/error_code.hpp>
+#include <boost/system/result.hpp>
 
 #include "src/detail/iocp/mutex.hpp"
 #include "src/detail/scheduler_op.hpp"
@@ -105,9 +106,9 @@ class win_signal_impl
         system::error_code*,
         int*) override;
 
-    system::error_code add(int signal_number) override;
-    system::error_code remove(int signal_number) override;
-    system::error_code clear() override;
+    system::result<void> add(int signal_number) override;
+    system::result<void> remove(int signal_number) override;
+    system::result<void> clear() override;
     void cancel() override;
 };
 
@@ -158,9 +159,9 @@ class win_signals : public capy::execution_context::service
 
         @param impl The signal implementation to modify.
         @param signal_number The signal to register.
-        @return Error code, or success.
+        @return Success, or an error.
     */
-    system::error_code add_signal(
+    system::result<void> add_signal(
         win_signal_impl& impl,
         int signal_number);
 
@@ -168,18 +169,18 @@ class win_signals : public capy::execution_context::service
 
         @param impl The signal implementation to modify.
         @param signal_number The signal to unregister.
-        @return Error code, or success.
+        @return Success, or an error.
     */
-    system::error_code remove_signal(
+    system::result<void> remove_signal(
         win_signal_impl& impl,
         int signal_number);
 
     /** Remove all signals from a signal set.
 
         @param impl The signal implementation to clear.
-        @return Error code, or success.
+        @return Success, or an error.
     */
-    system::error_code clear_signals(win_signal_impl& impl);
+    system::result<void> clear_signals(win_signal_impl& impl);
 
     /** Cancel pending wait operations.
 
diff --git a/test/unit/signal_set.cpp b/test/unit/signal_set.cpp
index 3263647..29dc71b 100644
--- a/test/unit/signal_set.cpp
+++ b/test/unit/signal_set.cpp
@@ -113,19 +113,8 @@ struct signal_set_test
         io_context ioc;
         signal_set s(ioc);
 
-        s.add(SIGINT);
-        BOOST_TEST_PASS();
-    }
-
-    void
-    testAddWithErrorCode()
-    {
-        io_context ioc;
-        signal_set s(ioc);
-
-        system::error_code ec;
-        s.add(SIGINT, ec);
-        BOOST_TEST(!ec);
+        auto result = s.add(SIGINT);
+        BOOST_TEST(result.has_value());
     }
 
     void
@@ -134,9 +123,9 @@ struct signal_set_test
         io_context ioc;
         signal_set s(ioc);
 
-        s.add(SIGINT);
-        s.add(SIGINT);  // Should be no-op
-        BOOST_TEST_PASS();
+        BOOST_TEST(s.add(SIGINT).has_value());
+        auto result = s.add(SIGINT);  // Should be no-op
+        BOOST_TEST(result.has_value());
     }
 
     void
@@ -145,9 +134,8 @@ struct signal_set_test
         io_context ioc;
         signal_set s(ioc);
 
-        system::error_code ec;
-        s.add(-1, ec);
-        BOOST_TEST(ec);
+        auto result = s.add(-1);
+        BOOST_TEST(result.has_error());
     }
 
     void
@@ -156,21 +144,9 @@ struct signal_set_test
         io_context ioc;
         signal_set s(ioc);
 
-        s.add(SIGINT);
-        s.remove(SIGINT);
-        BOOST_TEST_PASS();
-    }
-
-    void
-    testRemoveWithErrorCode()
-    {
-        io_context ioc;
-        signal_set s(ioc);
-
-        s.add(SIGINT);
-        system::error_code ec;
-        s.remove(SIGINT, ec);
-        BOOST_TEST(!ec);
+        BOOST_TEST(s.add(SIGINT).has_value());
+        auto result = s.remove(SIGINT);
+        BOOST_TEST(result.has_value());
     }
 
     void
@@ -180,8 +156,8 @@ struct signal_set_test
         signal_set s(ioc);
 
         // Removing signal not in set should be a no-op
-        s.remove(SIGINT);
-        BOOST_TEST_PASS();
+        auto result = s.remove(SIGINT);
+        BOOST_TEST(result.has_value());
     }
 
     void
@@ -190,22 +166,9 @@ struct signal_set_test
         io_context ioc;
         signal_set s(ioc);
 
-        s.add(SIGINT);
-        s.add(SIGTERM);
-        s.clear();
-        BOOST_TEST_PASS();
-    }
-
-    void
-    testClearWithErrorCode()
-    {
-        io_context ioc;
-        signal_set s(ioc);
-
-        s.add(SIGINT);
-        system::error_code ec;
-        s.clear(ec);
-        BOOST_TEST(!ec);
+        BOOST_TEST(s.add(SIGINT).has_value());
+        BOOST_TEST(s.add(SIGTERM).has_value());
+        BOOST_TEST(s.clear().has_value());
     }
 
     void
@@ -214,8 +177,7 @@ struct signal_set_test
         io_context ioc;
         signal_set s(ioc);
 
-        s.clear();  // Should be no-op
-        BOOST_TEST_PASS();
+        BOOST_TEST(s.clear().has_value());  // Should be no-op
     }
 
     //--------------------------------------------
@@ -593,14 +555,11 @@ struct signal_set_test
 
         // Add/remove/clear tests
         testAdd();
-        testAddWithErrorCode();
         testAddDuplicate();
         testAddInvalidSignal();
         testRemove();
-        testRemoveWithErrorCode();
         testRemoveNotPresent();
         testClear();
-        testClearWithErrorCode();
         testClearEmpty();
 
         // Async wait tests