diff --git a/include/boost/mysql/connection.hpp b/include/boost/mysql/connection.hpp
index d8e2480e..249102a5 100644
--- a/include/boost/mysql/connection.hpp
+++ b/include/boost/mysql/connection.hpp
@@ -207,7 +207,7 @@ public:
      */
     template <
         typename EndpointType,
-        BOOST_ASIO_COMPLETION_TOKEN_FOR(void(error_code))
+        BOOST_ASIO_COMPLETION_TOKEN_FOR(void(::boost::mysql::error_code))
         CompletionToken
         BOOST_ASIO_DEFAULT_COMPLETION_TOKEN_TYPE(executor_type)
     >
@@ -242,7 +242,7 @@ public:
      */
     template <
         typename EndpointType,
-        BOOST_ASIO_COMPLETION_TOKEN_FOR(void(error_code))
+        BOOST_ASIO_COMPLETION_TOKEN_FOR(void(::boost::mysql::error_code))
         CompletionToken
         BOOST_ASIO_DEFAULT_COMPLETION_TOKEN_TYPE(executor_type)
     >
@@ -291,7 +291,7 @@ public:
      * The handler signature for this operation is `void(boost::mysql::error_code)`.
      */
     template <
-        BOOST_ASIO_COMPLETION_TOKEN_FOR(void(error_code))
+        BOOST_ASIO_COMPLETION_TOKEN_FOR(void(::boost::mysql::error_code))
         CompletionToken
         BOOST_ASIO_DEFAULT_COMPLETION_TOKEN_TYPE(executor_type)
     >
@@ -319,7 +319,7 @@ public:
      * The handler signature for this operation is `void(boost::mysql::error_code)`.
      */
     template <
-        BOOST_ASIO_COMPLETION_TOKEN_FOR(void(error_code))
+        BOOST_ASIO_COMPLETION_TOKEN_FOR(void(::boost::mysql::error_code))
         CompletionToken
         BOOST_ASIO_DEFAULT_COMPLETION_TOKEN_TYPE(executor_type)
     >
@@ -362,7 +362,9 @@ public:
      * `void(boost::mysql::error_code, boost::mysql::resultset<Stream>)`.
      */
     template <
-        BOOST_ASIO_COMPLETION_TOKEN_FOR(void(error_code, resultset<Stream>))
+        BOOST_ASIO_COMPLETION_TOKEN_FOR(
+            void(::boost::mysql::error_code, ::boost::mysql::resultset<Stream>)
+        )
         CompletionToken
         BOOST_ASIO_DEFAULT_COMPLETION_TOKEN_TYPE(executor_type)
     >
@@ -387,7 +389,9 @@ public:
      * `void(boost::mysql::error_code, boost::mysql::resultset<Stream>)`.
      */
     template <
-        BOOST_ASIO_COMPLETION_TOKEN_FOR(void(error_code, resultset<Stream>))
+        BOOST_ASIO_COMPLETION_TOKEN_FOR(
+            void(::boost::mysql::error_code, ::boost::mysql::resultset<Stream>)
+        )
         CompletionToken
         BOOST_ASIO_DEFAULT_COMPLETION_TOKEN_TYPE(executor_type)
     >
@@ -424,7 +428,9 @@ public:
      * `void(boost::mysql::error_code, boost::mysql::prepared_statement<Stream>)`
      */
     template <
-        BOOST_ASIO_COMPLETION_TOKEN_FOR(void(error_code, prepared_statement<Stream>))
+        BOOST_ASIO_COMPLETION_TOKEN_FOR(
+            void(::boost::mysql::error_code, ::boost::mysql::prepared_statement<Stream>)
+        )
         CompletionToken
         BOOST_ASIO_DEFAULT_COMPLETION_TOKEN_TYPE(executor_type)
     >
@@ -447,7 +453,9 @@ public:
      * `void(boost::mysql::error_code, boost::mysql::prepared_statement<Stream>)`
      */
     template <
-        BOOST_ASIO_COMPLETION_TOKEN_FOR(void(error_code, prepared_statement<Stream>))
+        BOOST_ASIO_COMPLETION_TOKEN_FOR(
+            void(::boost::mysql::error_code, ::boost::mysql::prepared_statement<Stream>)
+        )
         CompletionToken
         BOOST_ASIO_DEFAULT_COMPLETION_TOKEN_TYPE(executor_type)
     >
@@ -493,7 +501,7 @@ public:
      * The handler signature for this operation is `void(boost::mysql::error_code)`.
      */
     template <
-        BOOST_ASIO_COMPLETION_TOKEN_FOR(void(error_code))
+        BOOST_ASIO_COMPLETION_TOKEN_FOR(void(::boost::mysql::error_code))
         CompletionToken
         BOOST_ASIO_DEFAULT_COMPLETION_TOKEN_TYPE(executor_type)
     >
@@ -515,7 +523,7 @@ public:
      * The handler signature for this operation is `void(boost::mysql::error_code)`.
      */
     template <
-        BOOST_ASIO_COMPLETION_TOKEN_FOR(void(error_code))
+        BOOST_ASIO_COMPLETION_TOKEN_FOR(void(::boost::mysql::error_code))
         CompletionToken
         BOOST_ASIO_DEFAULT_COMPLETION_TOKEN_TYPE(executor_type)
     >
@@ -570,7 +578,7 @@ public:
      * The handler signature for this operation is `void(boost::mysql::error_code)`.
      */
     template <
-        BOOST_ASIO_COMPLETION_TOKEN_FOR(void(error_code))
+        BOOST_ASIO_COMPLETION_TOKEN_FOR(void(::boost::mysql::error_code))
         CompletionToken
         BOOST_ASIO_DEFAULT_COMPLETION_TOKEN_TYPE(executor_type)
     >
@@ -595,7 +603,7 @@ public:
      * The handler signature for this operation is `void(boost::mysql::error_code)`.
      */
     template <
-        BOOST_ASIO_COMPLETION_TOKEN_FOR(void(error_code))
+        BOOST_ASIO_COMPLETION_TOKEN_FOR(void(::boost::mysql::error_code))
         CompletionToken
         BOOST_ASIO_DEFAULT_COMPLETION_TOKEN_TYPE(executor_type)
     >
diff --git a/include/boost/mysql/impl/connection.hpp b/include/boost/mysql/impl/connection.hpp
index 5bdae51d..10e3f529 100644
--- a/include/boost/mysql/impl/connection.hpp
+++ b/include/boost/mysql/impl/connection.hpp
@@ -48,7 +48,7 @@ void boost::mysql::connection<Stream>::connect(
 template <class Stream>
 template <
     class EndpointType,
-    BOOST_ASIO_COMPLETION_TOKEN_FOR(void(boost::mysql::error_code)) CompletionToken
+    BOOST_ASIO_COMPLETION_TOKEN_FOR(void(::boost::mysql::error_code)) CompletionToken
 >
 BOOST_ASIO_INITFN_AUTO_RESULT_TYPE(
     CompletionToken,
@@ -93,7 +93,7 @@ void boost::mysql::connection<Stream>::handshake(
 }
 
 template <class Stream>
-template <BOOST_ASIO_COMPLETION_TOKEN_FOR(void(boost::mysql::error_code)) CompletionToken>
+template <BOOST_ASIO_COMPLETION_TOKEN_FOR(void(::boost::mysql::error_code)) CompletionToken>
 BOOST_ASIO_INITFN_AUTO_RESULT_TYPE(
     CompletionToken,
     void(boost::mysql::error_code)
@@ -141,7 +141,8 @@ boost::mysql::resultset<Stream> boost::mysql::connection<Stream>::query(
 
 template <class Stream>
 template <BOOST_ASIO_COMPLETION_TOKEN_FOR(
-    void(boost::mysql::error_code, boost::mysql::resultset<Stream>)) CompletionToken>
+    void(::boost::mysql::error_code, ::boost::mysql::resultset<Stream>)
+) CompletionToken>
 BOOST_ASIO_INITFN_AUTO_RESULT_TYPE(
     CompletionToken,
     void(boost::mysql::error_code, boost::mysql::resultset<Stream>)
@@ -188,7 +189,8 @@ boost::mysql::prepared_statement<Stream> boost::mysql::connection<Stream>::prepa
 
 template <class Stream>
 template <BOOST_ASIO_COMPLETION_TOKEN_FOR(
-    void(boost::mysql::error_code, boost::mysql::prepared_statement<Stream>)) CompletionToken>
+    void(::boost::mysql::error_code, ::boost::mysql::prepared_statement<Stream>)
+) CompletionToken>
 BOOST_ASIO_INITFN_AUTO_RESULT_TYPE(
     CompletionToken,
     void(boost::mysql::error_code, boost::mysql::prepared_statement<Stream>)
@@ -228,7 +230,7 @@ void boost::mysql::connection<Stream>::close()
 }
 
 template <class Stream>
-template <BOOST_ASIO_COMPLETION_TOKEN_FOR(void(boost::mysql::error_code)) CompletionToken>
+template <BOOST_ASIO_COMPLETION_TOKEN_FOR(void(::boost::mysql::error_code)) CompletionToken>
 BOOST_ASIO_INITFN_AUTO_RESULT_TYPE(
     CompletionToken,
     void(boost::mysql::error_code)
@@ -265,7 +267,7 @@ void boost::mysql::connection<Stream>::quit()
 }
 
 template <class Stream>
-template <BOOST_ASIO_COMPLETION_TOKEN_FOR(void(boost::mysql::error_code)) CompletionToken>
+template <BOOST_ASIO_COMPLETION_TOKEN_FOR(void(::boost::mysql::error_code)) CompletionToken>
 BOOST_ASIO_INITFN_AUTO_RESULT_TYPE(
     CompletionToken,
     void(boost::mysql::error_code)
diff --git a/include/boost/mysql/impl/prepared_statement.hpp b/include/boost/mysql/impl/prepared_statement.hpp
index 86507526..81e81994 100644
--- a/include/boost/mysql/impl/prepared_statement.hpp
+++ b/include/boost/mysql/impl/prepared_statement.hpp
@@ -134,7 +134,8 @@ struct boost::mysql::prepared_statement<Stream>::async_execute_initiation
 
 template <class Stream>
 template <class ValueForwardIterator, BOOST_ASIO_COMPLETION_TOKEN_FOR(
-    void(boost::mysql::error_code, boost::mysql::resultset<Stream>)) CompletionToken>
+    void(::boost::mysql::error_code, ::boost::mysql::resultset<Stream>)
+) CompletionToken>
 BOOST_ASIO_INITFN_AUTO_RESULT_TYPE(
     CompletionToken,
     void(boost::mysql::error_code, boost::mysql::resultset<Stream>)
@@ -184,7 +185,7 @@ void boost::mysql::prepared_statement<Stream>::close()
 }
 
 template <class Stream>
-template <BOOST_ASIO_COMPLETION_TOKEN_FOR(void(boost::mysql::error_code)) CompletionToken>
+template <BOOST_ASIO_COMPLETION_TOKEN_FOR(void(::boost::mysql::error_code)) CompletionToken>
 BOOST_ASIO_INITFN_AUTO_RESULT_TYPE(
     CompletionToken,
     void(boost::mysql::error_code)
diff --git a/include/boost/mysql/impl/resultset.hpp b/include/boost/mysql/impl/resultset.hpp
index 952a2cdf..168c8562 100644
--- a/include/boost/mysql/impl/resultset.hpp
+++ b/include/boost/mysql/impl/resultset.hpp
@@ -172,7 +172,7 @@ struct boost::mysql::resultset<Stream>::read_one_op
 
 template <class Stream>
 template <BOOST_ASIO_COMPLETION_TOKEN_FOR(
-    void(boost::mysql::error_code, bool)) CompletionToken>
+    void(::boost::mysql::error_code, bool)) CompletionToken>
 BOOST_ASIO_INITFN_AUTO_RESULT_TYPE(
     CompletionToken,
     void(boost::mysql::error_code, bool)
@@ -303,7 +303,7 @@ struct boost::mysql::resultset<Stream>::read_many_op
 
 template <class Stream>
 template <BOOST_ASIO_COMPLETION_TOKEN_FOR(
-    void(boost::mysql::error_code, std::vector<boost::mysql::row>)) CompletionToken>
+    void(::boost::mysql::error_code, std::vector<::boost::mysql::row>)) CompletionToken>
 BOOST_ASIO_INITFN_AUTO_RESULT_TYPE(
     CompletionToken,
     void(boost::mysql::error_code, std::vector<boost::mysql::row>)
@@ -328,7 +328,7 @@ boost::mysql::resultset<Stream>::async_read_many(
 
 template <class Stream>
 template <BOOST_ASIO_COMPLETION_TOKEN_FOR(
-    void(boost::mysql::error_code, std::vector<boost::mysql::row>)) CompletionToken>
+    void(::boost::mysql::error_code, std::vector<::boost::mysql::row>)) CompletionToken>
 BOOST_ASIO_INITFN_AUTO_RESULT_TYPE(
     CompletionToken,
     void(boost::mysql::error_code, std::vector<boost::mysql::row>)
diff --git a/include/boost/mysql/prepared_statement.hpp b/include/boost/mysql/prepared_statement.hpp
index adf2c914..b9a2ff64 100644
--- a/include/boost/mysql/prepared_statement.hpp
+++ b/include/boost/mysql/prepared_statement.hpp
@@ -153,7 +153,9 @@ public:
      */
     template <
         class ValueCollection,
-            BOOST_ASIO_COMPLETION_TOKEN_FOR(void(error_code, resultset<Stream>))
+            BOOST_ASIO_COMPLETION_TOKEN_FOR(
+                void(::boost::mysql::error_code, ::boost::mysql::resultset<Stream>)
+            )
             CompletionToken
             BOOST_ASIO_DEFAULT_COMPLETION_TOKEN_TYPE(executor_type),
             class EnableIf = detail::enable_if_value_collection<ValueCollection>
@@ -187,7 +189,9 @@ public:
      */
     template <
         class ValueCollection,
-            BOOST_ASIO_COMPLETION_TOKEN_FOR(void(error_code, resultset<Stream>))
+            BOOST_ASIO_COMPLETION_TOKEN_FOR(
+                void(::boost::mysql::error_code, ::boost::mysql::resultset<Stream>)
+            )
             CompletionToken
             BOOST_ASIO_DEFAULT_COMPLETION_TOKEN_TYPE(executor_type),
             class EnableIf = detail::enable_if_value_collection<ValueCollection>
@@ -257,7 +261,9 @@ public:
      */
     template <
         class ValueForwardIterator,
-            BOOST_ASIO_COMPLETION_TOKEN_FOR(void(error_code, resultset<Stream>))
+            BOOST_ASIO_COMPLETION_TOKEN_FOR(
+                void(::boost::mysql::error_code, ::boost::mysql::resultset<Stream>)
+            )
             CompletionToken
             BOOST_ASIO_DEFAULT_COMPLETION_TOKEN_TYPE(executor_type)
     >
@@ -291,7 +297,9 @@ public:
      */
     template <
         class ValueForwardIterator,
-            BOOST_ASIO_COMPLETION_TOKEN_FOR(void(error_code, resultset<Stream>))
+            BOOST_ASIO_COMPLETION_TOKEN_FOR(
+                void(::boost::mysql::error_code, ::boost::mysql::resultset<Stream>)
+            )
             CompletionToken
             BOOST_ASIO_DEFAULT_COMPLETION_TOKEN_TYPE(executor_type)
     >
@@ -330,7 +338,7 @@ public:
      * The handler signature for this operation is `void(boost::mysql::error_code)`.
      */
     template <
-        BOOST_ASIO_COMPLETION_TOKEN_FOR(void(error_code))
+        BOOST_ASIO_COMPLETION_TOKEN_FOR(void(::boost::mysql::error_code))
         CompletionToken
         BOOST_ASIO_DEFAULT_COMPLETION_TOKEN_TYPE(executor_type)
     >
@@ -350,7 +358,7 @@ public:
      * The handler signature for this operation is `void(boost::mysql::error_code)`.
      */
     template <
-        BOOST_ASIO_COMPLETION_TOKEN_FOR(void(error_code))
+        BOOST_ASIO_COMPLETION_TOKEN_FOR(void(::boost::mysql::error_code))
         CompletionToken
         BOOST_ASIO_DEFAULT_COMPLETION_TOKEN_TYPE(executor_type)
     >
diff --git a/include/boost/mysql/resultset.hpp b/include/boost/mysql/resultset.hpp
index c624b9f7..2fcb869d 100644
--- a/include/boost/mysql/resultset.hpp
+++ b/include/boost/mysql/resultset.hpp
@@ -137,7 +137,7 @@ class resultset
      * `void(boost::mysql::error_code, bool)`.
      */
     template <
-        BOOST_ASIO_COMPLETION_TOKEN_FOR(void(error_code, bool))
+        BOOST_ASIO_COMPLETION_TOKEN_FOR(void(::boost::mysql::error_code, bool))
         CompletionToken
         BOOST_ASIO_DEFAULT_COMPLETION_TOKEN_TYPE(executor_type)
     >
@@ -163,7 +163,7 @@ class resultset
      * `void(boost::mysql::error_code, bool)`.
      */
     template <
-        BOOST_ASIO_COMPLETION_TOKEN_FOR(void(error_code, bool))
+        BOOST_ASIO_COMPLETION_TOKEN_FOR(void(::boost::mysql::error_code, bool))
         CompletionToken
         BOOST_ASIO_DEFAULT_COMPLETION_TOKEN_TYPE(executor_type)
     >
@@ -188,7 +188,9 @@ class resultset
      * `void(boost::mysql::error_code, std::vector<boost::mysql::row>)`.
      */
     template <
-        BOOST_ASIO_COMPLETION_TOKEN_FOR(void(error_code, std::vector<row>))
+        BOOST_ASIO_COMPLETION_TOKEN_FOR(
+            void(::boost::mysql::error_code, std::vector<::boost::mysql::row>)
+        )
         CompletionToken
         BOOST_ASIO_DEFAULT_COMPLETION_TOKEN_TYPE(executor_type)
     >
@@ -209,7 +211,9 @@ class resultset
      * `void(boost::mysql::error_code, std::vector<boost::mysql::row>)`.
      */
     template <
-        BOOST_ASIO_COMPLETION_TOKEN_FOR(void(error_code, std::vector<row>))
+        BOOST_ASIO_COMPLETION_TOKEN_FOR(
+            void(::boost::mysql::error_code, std::vector<::boost::mysql::row>)
+        )
         CompletionToken
         BOOST_ASIO_DEFAULT_COMPLETION_TOKEN_TYPE(executor_type)
     >
@@ -233,7 +237,9 @@ class resultset
      * `void(boost::mysql::error_code, std::vector<boost::mysql::row>)`.
      */
     template <
-        BOOST_ASIO_COMPLETION_TOKEN_FOR(void(error_code, std::vector<row>))
+        BOOST_ASIO_COMPLETION_TOKEN_FOR(
+            void(::boost::mysql::error_code, std::vector<::boost::mysql::row>)
+        )
         CompletionToken
         BOOST_ASIO_DEFAULT_COMPLETION_TOKEN_TYPE(executor_type)
     >
@@ -250,7 +256,9 @@ class resultset
      * `void(boost::mysql::error_code, std::vector<boost::mysql::row>)`.
      */
     template <
-        BOOST_ASIO_COMPLETION_TOKEN_FOR(void(error_code, std::vector<row>))
+        BOOST_ASIO_COMPLETION_TOKEN_FOR(
+            void(::boost::mysql::error_code, std::vector<::boost::mysql::row>)
+        )
         CompletionToken
         BOOST_ASIO_DEFAULT_COMPLETION_TOKEN_TYPE(executor_type)
     >