diff --git a/batch.go b/batch.go
index 75252ef5..11397c2e 100644
--- a/batch.go
+++ b/batch.go
@@ -3,6 +3,7 @@ package pgx
 import (
 	"context"
 
+	"github.com/jackc/pgx/pgconn"
 	"github.com/jackc/pgx/pgproto3"
 	"github.com/jackc/pgx/pgtype"
 )
@@ -162,21 +163,21 @@ func (b *Batch) Send(ctx context.Context, txOptions *TxOptions) error {
 
 // ExecResults reads the results from the next query in the batch as if the
 // query has been sent with Exec.
-func (b *Batch) ExecResults() (CommandTag, error) {
+func (b *Batch) ExecResults() (pgconn.CommandTag, error) {
 	if b.err != nil {
-		return "", b.err
+		return nil, b.err
 	}
 
 	select {
 	case <-b.ctx.Done():
 		b.die(b.ctx.Err())
-		return "", b.ctx.Err()
+		return nil, b.ctx.Err()
 	default:
 	}
 
 	if err := b.ensureCommandComplete(); err != nil {
 		b.die(err)
-		return "", err
+		return nil, err
 	}
 
 	b.resultsRead++
@@ -186,16 +187,16 @@ func (b *Batch) ExecResults() (CommandTag, error) {
 	for {
 		msg, err := b.conn.rxMsg()
 		if err != nil {
-			return "", err
+			return nil, err
 		}
 
 		switch msg := msg.(type) {
 		case *pgproto3.CommandComplete:
 			b.pendingCommandComplete = false
-			return CommandTag(msg.CommandTag), nil
+			return pgconn.CommandTag(msg.CommandTag), nil
 		default:
 			if err := b.conn.processContextFreeMsg(msg); err != nil {
-				return "", err
+				return nil, err
 			}
 		}
 	}
diff --git a/conn.go b/conn.go
index 822b7b3e..e9db6b19 100644
--- a/conn.go
+++ b/conn.go
@@ -4,7 +4,6 @@ import (
 	"context"
 	"net"
 	"reflect"
-	"strconv"
 	"strings"
 	"sync"
 	"time"
@@ -120,21 +119,6 @@ type Notification struct {
 	Payload string
 }
 
-// CommandTag is the result of an Exec function
-type CommandTag string
-
-// RowsAffected returns the number of rows affected. If the CommandTag was not
-// for a row affecting command (such as "CREATE TABLE") then it returns 0
-func (ct CommandTag) RowsAffected() int64 {
-	s := string(ct)
-	index := strings.LastIndex(s, " ")
-	if index == -1 {
-		return 0
-	}
-	n, _ := strconv.ParseInt(s[index+1:], 10, 64)
-	return n
-}
-
 // Identifier a PostgreSQL identifier or name. Identifiers can be composed of
 // multiple parts such as ["schema", "table"] or ["table", "column"].
 type Identifier []string
@@ -855,7 +839,7 @@ func fatalWriteErr(bytesWritten int, err error) bool {
 
 // Exec executes sql. sql can be either a prepared statement name or an SQL string.
 // arguments should be referenced positionally from the sql string as $1, $2, etc.
-func (c *Conn) Exec(sql string, arguments ...interface{}) (commandTag CommandTag, err error) {
+func (c *Conn) Exec(sql string, arguments ...interface{}) (commandTag pgconn.CommandTag, err error) {
 	return c.ExecEx(context.Background(), sql, nil, arguments...)
 }
 
@@ -1104,15 +1088,15 @@ func (c *Conn) Ping(ctx context.Context) error {
 	return err
 }
 
-func (c *Conn) ExecEx(ctx context.Context, sql string, options *QueryExOptions, arguments ...interface{}) (CommandTag, error) {
+func (c *Conn) ExecEx(ctx context.Context, sql string, options *QueryExOptions, arguments ...interface{}) (pgconn.CommandTag, error) {
 	c.lastStmtSent = false
 	err := c.waitForPreviousCancelQuery(ctx)
 	if err != nil {
-		return "", err
+		return nil, err
 	}
 
 	if err := c.lock(); err != nil {
-		return "", err
+		return nil, err
 	}
 	defer c.unlock()
 
@@ -1134,10 +1118,10 @@ func (c *Conn) ExecEx(ctx context.Context, sql string, options *QueryExOptions,
 	return commandTag, err
 }
 
-func (c *Conn) execEx(ctx context.Context, sql string, options *QueryExOptions, arguments ...interface{}) (commandTag CommandTag, err error) {
+func (c *Conn) execEx(ctx context.Context, sql string, options *QueryExOptions, arguments ...interface{}) (commandTag pgconn.CommandTag, err error) {
 	err = c.initContext(ctx)
 	if err != nil {
-		return "", err
+		return nil, err
 	}
 	defer func() {
 		err = c.termContext(err)
@@ -1147,16 +1131,16 @@ func (c *Conn) execEx(ctx context.Context, sql string, options *QueryExOptions,
 		c.lastStmtSent = true
 		err = c.sanitizeAndSendSimpleQuery(sql, arguments...)
 		if err != nil {
-			return "", err
+			return nil, err
 		}
 	} else if options != nil && len(options.ParameterOIDs) > 0 {
 		if err := c.ensureConnectionReadyForQuery(); err != nil {
-			return "", err
+			return nil, err
 		}
 
 		buf, err := c.buildOneRoundTripExec(c.wbuf, sql, options, arguments)
 		if err != nil {
-			return "", err
+			return nil, err
 		}
 
 		buf = appendSync(buf)
@@ -1165,7 +1149,7 @@ func (c *Conn) execEx(ctx context.Context, sql string, options *QueryExOptions,
 		c.lastStmtSent = true
 		if err != nil && fatalWriteErr(n, err) {
 			c.die(err)
-			return "", err
+			return nil, err
 		}
 		c.pendingReadyForQueryCount++
 	} else {
@@ -1175,14 +1159,14 @@ func (c *Conn) execEx(ctx context.Context, sql string, options *QueryExOptions,
 				var err error
 				ps, err = c.prepareEx("", sql, nil)
 				if err != nil {
-					return "", err
+					return nil, err
 				}
 			}
 
 			c.lastStmtSent = true
 			err = c.sendPreparedQuery(ps, arguments...)
 			if err != nil {
-				return "", err
+				return nil, err
 			}
 		} else {
 			c.lastStmtSent = true
@@ -1205,7 +1189,7 @@ func (c *Conn) execEx(ctx context.Context, sql string, options *QueryExOptions,
 			c.rxReadyForQuery(msg)
 			return commandTag, softErr
 		case *pgproto3.CommandComplete:
-			commandTag = CommandTag(msg.CommandTag)
+			commandTag = pgconn.CommandTag(msg.CommandTag)
 		default:
 			if e := c.processContextFreeMsg(msg); e != nil && softErr == nil {
 				softErr = e
diff --git a/conn_pool.go b/conn_pool.go
index f857176d..eea043e7 100644
--- a/conn_pool.go
+++ b/conn_pool.go
@@ -8,6 +8,7 @@ import (
 
 	"github.com/pkg/errors"
 
+	"github.com/jackc/pgx/pgconn"
 	"github.com/jackc/pgx/pgtype"
 )
 
@@ -352,7 +353,7 @@ func (p *ConnPool) afterConnectionCreated(c *Conn) (*Conn, error) {
 }
 
 // Exec acquires a connection, delegates the call to that connection, and releases the connection
-func (p *ConnPool) Exec(sql string, arguments ...interface{}) (commandTag CommandTag, err error) {
+func (p *ConnPool) Exec(sql string, arguments ...interface{}) (commandTag pgconn.CommandTag, err error) {
 	var c *Conn
 	if c, err = p.Acquire(); err != nil {
 		return
@@ -362,7 +363,7 @@ func (p *ConnPool) Exec(sql string, arguments ...interface{}) (commandTag Comman
 	return c.Exec(sql, arguments...)
 }
 
-func (p *ConnPool) ExecEx(ctx context.Context, sql string, options *QueryExOptions, arguments ...interface{}) (commandTag CommandTag, err error) {
+func (p *ConnPool) ExecEx(ctx context.Context, sql string, options *QueryExOptions, arguments ...interface{}) (commandTag pgconn.CommandTag, err error) {
 	var c *Conn
 	if c, err = p.Acquire(); err != nil {
 		return
@@ -554,10 +555,10 @@ func (p *ConnPool) CopyFrom(tableName Identifier, columnNames []string, rowSrc C
 }
 
 // CopyFromReader acquires a connection, delegates the call to that connection, and releases the connection
-func (p *ConnPool) CopyFromReader(r io.Reader, sql string) (CommandTag, error) {
+func (p *ConnPool) CopyFromReader(r io.Reader, sql string) (pgconn.CommandTag, error) {
 	c, err := p.Acquire()
 	if err != nil {
-		return "", err
+		return nil, err
 	}
 	defer p.Release(c)
 
@@ -565,10 +566,10 @@ func (p *ConnPool) CopyFromReader(r io.Reader, sql string) (CommandTag, error) {
 }
 
 // CopyToWriter acquires a connection, delegates the call to that connection, and releases the connection
-func (p *ConnPool) CopyToWriter(w io.Writer, sql string, args ...interface{}) (CommandTag, error) {
+func (p *ConnPool) CopyToWriter(w io.Writer, sql string, args ...interface{}) (pgconn.CommandTag, error) {
 	c, err := p.Acquire()
 	if err != nil {
-		return "", err
+		return nil, err
 	}
 	defer p.Release(c)
 
diff --git a/conn_pool_test.go b/conn_pool_test.go
index aed9d00f..168a3bc9 100644
--- a/conn_pool_test.go
+++ b/conn_pool_test.go
@@ -845,7 +845,7 @@ func TestConnPoolExec(t *testing.T) {
 	if err != nil {
 		t.Fatalf("Unexpected error from pool.Exec: %v", err)
 	}
-	if results != "CREATE TABLE" {
+	if string(results) != "CREATE TABLE" {
 		t.Errorf("Unexpected results from Exec: %v", results)
 	}
 
@@ -853,7 +853,7 @@ func TestConnPoolExec(t *testing.T) {
 	if err != nil {
 		t.Fatalf("Unexpected error from pool.Exec: %v", err)
 	}
-	if results != "INSERT 0 1" {
+	if string(results) != "INSERT 0 1" {
 		t.Errorf("Unexpected results from Exec: %v", results)
 	}
 
@@ -861,7 +861,7 @@ func TestConnPoolExec(t *testing.T) {
 	if err != nil {
 		t.Fatalf("Unexpected error from pool.Exec: %v", err)
 	}
-	if results != "DROP TABLE" {
+	if string(results) != "DROP TABLE" {
 		t.Errorf("Unexpected results from Exec: %v", results)
 	}
 }
diff --git a/conn_test.go b/conn_test.go
index 784f3168..b49ae174 100644
--- a/conn_test.go
+++ b/conn_test.go
@@ -111,31 +111,31 @@ func TestExec(t *testing.T) {
 	conn := mustConnectString(t, os.Getenv("PGX_TEST_DATABASE"))
 	defer closeConn(t, conn)
 
-	if results := mustExec(t, conn, "create temporary table foo(id integer primary key);"); results != "CREATE TABLE" {
+	if results := mustExec(t, conn, "create temporary table foo(id integer primary key);"); string(results) != "CREATE TABLE" {
 		t.Error("Unexpected results from Exec")
 	}
 
 	// Accept parameters
-	if results := mustExec(t, conn, "insert into foo(id) values($1)", 1); results != "INSERT 0 1" {
+	if results := mustExec(t, conn, "insert into foo(id) values($1)", 1); string(results) != "INSERT 0 1" {
 		t.Errorf("Unexpected results from Exec: %v", results)
 	}
 
-	if results := mustExec(t, conn, "drop table foo;"); results != "DROP TABLE" {
+	if results := mustExec(t, conn, "drop table foo;"); string(results) != "DROP TABLE" {
 		t.Error("Unexpected results from Exec")
 	}
 
 	// Multiple statements can be executed -- last command tag is returned
-	if results := mustExec(t, conn, "create temporary table foo(id serial primary key); drop table foo;"); results != "DROP TABLE" {
+	if results := mustExec(t, conn, "create temporary table foo(id serial primary key); drop table foo;"); string(results) != "DROP TABLE" {
 		t.Error("Unexpected results from Exec")
 	}
 
 	// Can execute longer SQL strings than sharedBufferSize
-	if results := mustExec(t, conn, strings.Repeat("select 42; ", 1000)); results != "SELECT 1" {
+	if results := mustExec(t, conn, strings.Repeat("select 42; ", 1000)); string(results) != "SELECT 1" {
 		t.Errorf("Unexpected results from Exec: %v", results)
 	}
 
 	// Exec no-op which does not return a command tag
-	if results := mustExec(t, conn, "--;"); results != "" {
+	if results := mustExec(t, conn, "--;"); string(results) != "" {
 		t.Errorf("Unexpected results from Exec: %v", results)
 	}
 }
@@ -190,7 +190,7 @@ func TestExecExContextWithoutCancelation(t *testing.T) {
 	if err != nil {
 		t.Fatal(err)
 	}
-	if commandTag != "CREATE TABLE" {
+	if string(commandTag) != "CREATE TABLE" {
 		t.Fatalf("Unexpected results from ExecEx: %v", commandTag)
 	}
 	if !conn.LastStmtSent() {
@@ -291,7 +291,7 @@ func TestExecExExtendedProtocol(t *testing.T) {
 	if err != nil {
 		t.Fatal(err)
 	}
-	if commandTag != "CREATE TABLE" {
+	if string(commandTag) != "CREATE TABLE" {
 		t.Fatalf("Unexpected results from ExecEx: %v", commandTag)
 	}
 
@@ -304,7 +304,7 @@ func TestExecExExtendedProtocol(t *testing.T) {
 	if err != nil {
 		t.Fatal(err)
 	}
-	if commandTag != "INSERT 0 1" {
+	if string(commandTag) != "INSERT 0 1" {
 		t.Fatalf("Unexpected results from ExecEx: %v", commandTag)
 	}
 
@@ -324,7 +324,7 @@ func TestExecExSimpleProtocol(t *testing.T) {
 	if err != nil {
 		t.Fatal(err)
 	}
-	if commandTag != "CREATE TABLE" {
+	if string(commandTag) != "CREATE TABLE" {
 		t.Fatalf("Unexpected results from ExecEx: %v", commandTag)
 	}
 	if !conn.LastStmtSent() {
@@ -340,7 +340,7 @@ func TestExecExSimpleProtocol(t *testing.T) {
 	if err != nil {
 		t.Fatal(err)
 	}
-	if commandTag != "INSERT 0 1" {
+	if string(commandTag) != "INSERT 0 1" {
 		t.Fatalf("Unexpected results from ExecEx: %v", commandTag)
 	}
 	if !conn.LastStmtSent() {
@@ -365,7 +365,7 @@ func TestConnExecExSuppliedCorrectParameterOIDs(t *testing.T) {
 	if err != nil {
 		t.Fatal(err)
 	}
-	if commandTag != "INSERT 0 1" {
+	if string(commandTag) != "INSERT 0 1" {
 		t.Fatalf("Unexpected results from ExecEx: %v", commandTag)
 	}
 	if !conn.LastStmtSent() {
@@ -924,43 +924,18 @@ func TestFatalTxError(t *testing.T) {
 	}
 }
 
-func TestCommandTag(t *testing.T) {
-	t.Parallel()
-
-	var tests = []struct {
-		commandTag   pgx.CommandTag
-		rowsAffected int64
-	}{
-		{commandTag: "INSERT 0 5", rowsAffected: 5},
-		{commandTag: "UPDATE 0", rowsAffected: 0},
-		{commandTag: "UPDATE 1", rowsAffected: 1},
-		{commandTag: "DELETE 0", rowsAffected: 0},
-		{commandTag: "DELETE 1", rowsAffected: 1},
-		{commandTag: "CREATE TABLE", rowsAffected: 0},
-		{commandTag: "ALTER TABLE", rowsAffected: 0},
-		{commandTag: "DROP TABLE", rowsAffected: 0},
-	}
-
-	for i, tt := range tests {
-		actual := tt.commandTag.RowsAffected()
-		if tt.rowsAffected != actual {
-			t.Errorf(`%d. "%s" should have affected %d rows but it was %d`, i, tt.commandTag, tt.rowsAffected, actual)
-		}
-	}
-}
-
 func TestInsertBoolArray(t *testing.T) {
 	t.Parallel()
 
 	conn := mustConnectString(t, os.Getenv("PGX_TEST_DATABASE"))
 	defer closeConn(t, conn)
 
-	if results := mustExec(t, conn, "create temporary table foo(spice bool[]);"); results != "CREATE TABLE" {
+	if results := mustExec(t, conn, "create temporary table foo(spice bool[]);"); string(results) != "CREATE TABLE" {
 		t.Error("Unexpected results from Exec")
 	}
 
 	// Accept parameters
-	if results := mustExec(t, conn, "insert into foo(spice) values($1)", []bool{true, false, true}); results != "INSERT 0 1" {
+	if results := mustExec(t, conn, "insert into foo(spice) values($1)", []bool{true, false, true}); string(results) != "INSERT 0 1" {
 		t.Errorf("Unexpected results from Exec: %v", results)
 	}
 }
@@ -971,12 +946,12 @@ func TestInsertTimestampArray(t *testing.T) {
 	conn := mustConnectString(t, os.Getenv("PGX_TEST_DATABASE"))
 	defer closeConn(t, conn)
 
-	if results := mustExec(t, conn, "create temporary table foo(spice timestamp[]);"); results != "CREATE TABLE" {
+	if results := mustExec(t, conn, "create temporary table foo(spice timestamp[]);"); string(results) != "CREATE TABLE" {
 		t.Error("Unexpected results from Exec")
 	}
 
 	// Accept parameters
-	if results := mustExec(t, conn, "insert into foo(spice) values($1)", []time.Time{time.Unix(1419143667, 0), time.Unix(1419143672, 0)}); results != "INSERT 0 1" {
+	if results := mustExec(t, conn, "insert into foo(spice) values($1)", []time.Time{time.Unix(1419143667, 0), time.Unix(1419143672, 0)}); string(results) != "INSERT 0 1" {
 		t.Errorf("Unexpected results from Exec: %v", results)
 	}
 }
diff --git a/copy_from.go b/copy_from.go
index 0bdfb315..8904f419 100644
--- a/copy_from.go
+++ b/copy_from.go
@@ -5,6 +5,7 @@ import (
 	"fmt"
 	"io"
 
+	"github.com/jackc/pgx/pgconn"
 	"github.com/jackc/pgx/pgio"
 	"github.com/jackc/pgx/pgproto3"
 	"github.com/pkg/errors"
@@ -284,13 +285,13 @@ func (c *Conn) CopyFrom(tableName Identifier, columnNames []string, rowSrc CopyF
 }
 
 // CopyFromReader uses the PostgreSQL textual format of the copy protocol
-func (c *Conn) CopyFromReader(r io.Reader, sql string) (CommandTag, error) {
+func (c *Conn) CopyFromReader(r io.Reader, sql string) (pgconn.CommandTag, error) {
 	if err := c.sendSimpleQuery(sql); err != nil {
-		return "", err
+		return nil, err
 	}
 
 	if err := c.readUntilCopyInResponse(); err != nil {
-		return "", err
+		return nil, err
 	}
 	buf := c.wbuf
 
@@ -305,7 +306,7 @@ func (c *Conn) CopyFromReader(r io.Reader, sql string) (CommandTag, error) {
 		pgio.SetInt32(buf[sp:], int32(n+4))
 
 		if _, err := c.pgConn.Conn().Write(buf); err != nil {
-			return "", err
+			return nil, err
 		}
 	}
 
@@ -314,25 +315,25 @@ func (c *Conn) CopyFromReader(r io.Reader, sql string) (CommandTag, error) {
 	buf = pgio.AppendInt32(buf, 4)
 
 	if _, err := c.pgConn.Conn().Write(buf); err != nil {
-		return "", err
+		return nil, err
 	}
 
 	for {
 		msg, err := c.rxMsg()
 		if err != nil {
-			return "", err
+			return nil, err
 		}
 
 		switch msg := msg.(type) {
 		case *pgproto3.ReadyForQuery:
 			c.rxReadyForQuery(msg)
-			return "", err
+			return nil, err
 		case *pgproto3.CommandComplete:
-			return CommandTag(msg.CommandTag), nil
+			return pgconn.CommandTag(msg.CommandTag), nil
 		case *pgproto3.ErrorResponse:
-			return "", c.rxErrorResponse(msg)
+			return nil, c.rxErrorResponse(msg)
 		default:
-			return "", c.processContextFreeMsg(msg)
+			return nil, c.processContextFreeMsg(msg)
 		}
 	}
 }
diff --git a/copy_to.go b/copy_to.go
index c85a0aa8..3af307a3 100644
--- a/copy_to.go
+++ b/copy_to.go
@@ -3,6 +3,7 @@ package pgx
 import (
 	"io"
 
+	"github.com/jackc/pgx/pgconn"
 	"github.com/jackc/pgx/pgproto3"
 )
 
@@ -25,19 +26,19 @@ func (c *Conn) readUntilCopyOutResponse() error {
 	}
 }
 
-func (c *Conn) CopyToWriter(w io.Writer, sql string, args ...interface{}) (CommandTag, error) {
+func (c *Conn) CopyToWriter(w io.Writer, sql string, args ...interface{}) (pgconn.CommandTag, error) {
 	if err := c.sendSimpleQuery(sql, args...); err != nil {
-		return "", err
+		return nil, err
 	}
 
 	if err := c.readUntilCopyOutResponse(); err != nil {
-		return "", err
+		return nil, err
 	}
 
 	for {
 		msg, err := c.rxMsg()
 		if err != nil {
-			return "", err
+			return nil, err
 		}
 
 		switch msg := msg.(type) {
@@ -47,17 +48,17 @@ func (c *Conn) CopyToWriter(w io.Writer, sql string, args ...interface{}) (Comma
 			_, err := w.Write(msg.Data)
 			if err != nil {
 				c.die(err)
-				return "", err
+				return nil, err
 			}
 		case *pgproto3.ReadyForQuery:
 			c.rxReadyForQuery(msg)
-			return "", nil
+			return nil, nil
 		case *pgproto3.CommandComplete:
-			return CommandTag(msg.CommandTag), nil
+			return pgconn.CommandTag(msg.CommandTag), nil
 		case *pgproto3.ErrorResponse:
-			return "", c.rxErrorResponse(msg)
+			return nil, c.rxErrorResponse(msg)
 		default:
-			return "", c.processContextFreeMsg(msg)
+			return nil, c.processContextFreeMsg(msg)
 		}
 	}
 }
diff --git a/helper_test.go b/helper_test.go
index e83e5ed6..188876c4 100644
--- a/helper_test.go
+++ b/helper_test.go
@@ -53,7 +53,7 @@ func closeReplicationConn(t testing.TB, conn *pgx.ReplicationConn) {
 	}
 }
 
-func mustExec(t testing.TB, conn *pgx.Conn, sql string, arguments ...interface{}) (commandTag pgx.CommandTag) {
+func mustExec(t testing.TB, conn *pgx.Conn, sql string, arguments ...interface{}) (commandTag pgconn.CommandTag) {
 	var err error
 	if commandTag, err = conn.Exec(sql, arguments...); err != nil {
 		t.Fatalf("Exec unexpectedly failed with %v: %v", sql, err)
diff --git a/pgconn/pgconn_test.go b/pgconn/pgconn_test.go
index 8b578d42..8f976d87 100644
--- a/pgconn/pgconn_test.go
+++ b/pgconn/pgconn_test.go
@@ -512,3 +512,26 @@ func TestConnCancelQuery(t *testing.T) {
 		t.Errorf("expected pgconn.PgError got %v", err)
 	}
 }
+
+func TestCommandTag(t *testing.T) {
+	t.Parallel()
+
+	var tests = []struct {
+		commandTag   pgconn.CommandTag
+		rowsAffected int64
+	}{
+		{commandTag: pgconn.CommandTag("INSERT 0 5"), rowsAffected: 5},
+		{commandTag: pgconn.CommandTag("UPDATE 0"), rowsAffected: 0},
+		{commandTag: pgconn.CommandTag("UPDATE 1"), rowsAffected: 1},
+		{commandTag: pgconn.CommandTag("DELETE 0"), rowsAffected: 0},
+		{commandTag: pgconn.CommandTag("DELETE 1"), rowsAffected: 1},
+		{commandTag: pgconn.CommandTag("CREATE TABLE"), rowsAffected: 0},
+		{commandTag: pgconn.CommandTag("ALTER TABLE"), rowsAffected: 0},
+		{commandTag: pgconn.CommandTag("DROP TABLE"), rowsAffected: 0},
+	}
+
+	for i, tt := range tests {
+		actual := tt.commandTag.RowsAffected()
+		assert.Equalf(t, tt.rowsAffected, actual, "%d. %v", i, tt.commandTag)
+	}
+}
diff --git a/query_test.go b/query_test.go
index 07e7b2c4..738e2ba6 100644
--- a/query_test.go
+++ b/query_test.go
@@ -1087,7 +1087,7 @@ func TestConnQueryDatabaseSQLDriverValuerWithAutoGeneratedPointerReceiver(t *tes
 	if err != nil {
 		t.Fatal(err)
 	}
-	if commandTag != "INSERT 0 1" {
+	if string(commandTag) != "INSERT 0 1" {
 		t.Fatalf("want %s, got %s", "INSERT 0 1", commandTag)
 	}
 
diff --git a/replication_test.go b/replication_test.go
index 0bd9a5d2..3ceac156 100644
--- a/replication_test.go
+++ b/replication_test.go
@@ -11,6 +11,7 @@ import (
 	"time"
 
 	"github.com/jackc/pgx"
+	"github.com/jackc/pgx/pgconn"
 )
 
 // This function uses a postgresql 9.6 specific column
@@ -87,7 +88,7 @@ func TestSimpleReplicationConnection(t *testing.T) {
 	currentTime := time.Now().Unix()
 
 	for i := 0; i < 5; i++ {
-		var ct pgx.CommandTag
+		var ct pgconn.CommandTag
 		insertedTimes = append(insertedTimes, currentTime)
 		ct, err = conn.Exec("insert into replication_test(a) values($1)", currentTime)
 		if err != nil {
diff --git a/stress_test.go b/stress_test.go
index 6ee49c5e..00ea33ef 100644
--- a/stress_test.go
+++ b/stress_test.go
@@ -17,7 +17,7 @@ import (
 )
 
 type execer interface {
-	Exec(sql string, arguments ...interface{}) (commandTag pgx.CommandTag, err error)
+	Exec(sql string, arguments ...interface{}) (commandTag pgconn.CommandTag, err error)
 }
 type queryer interface {
 	Query(sql string, args ...interface{}) (*pgx.Rows, error)
diff --git a/tx.go b/tx.go
index 30b0ede3..f82c5d24 100644
--- a/tx.go
+++ b/tx.go
@@ -7,6 +7,7 @@ import (
 	"io"
 	"time"
 
+	"github.com/jackc/pgx/pgconn"
 	"github.com/pkg/errors"
 )
 
@@ -123,9 +124,9 @@ func (tx *Tx) CommitEx(ctx context.Context) error {
 	}
 
 	commandTag, err := tx.conn.ExecEx(ctx, "commit", nil)
-	if err == nil && commandTag == "COMMIT" {
+	if err == nil && string(commandTag) == "COMMIT" {
 		tx.status = TxStatusCommitSuccess
-	} else if err == nil && commandTag == "ROLLBACK" {
+	} else if err == nil && string(commandTag) == "ROLLBACK" {
 		tx.status = TxStatusCommitFailure
 		tx.err = ErrTxCommitRollback
 	} else {
@@ -175,14 +176,14 @@ func (tx *Tx) RollbackEx(ctx context.Context) error {
 }
 
 // Exec delegates to the underlying *Conn
-func (tx *Tx) Exec(sql string, arguments ...interface{}) (commandTag CommandTag, err error) {
+func (tx *Tx) Exec(sql string, arguments ...interface{}) (commandTag pgconn.CommandTag, err error) {
 	return tx.ExecEx(context.Background(), sql, nil, arguments...)
 }
 
 // ExecEx delegates to the underlying *Conn
-func (tx *Tx) ExecEx(ctx context.Context, sql string, options *QueryExOptions, arguments ...interface{}) (commandTag CommandTag, err error) {
+func (tx *Tx) ExecEx(ctx context.Context, sql string, options *QueryExOptions, arguments ...interface{}) (commandTag pgconn.CommandTag, err error) {
 	if tx.status != TxStatusInProgress {
-		return CommandTag(""), ErrTxClosed
+		return nil, ErrTxClosed
 	}
 
 	return tx.conn.ExecEx(ctx, sql, options, arguments...)
@@ -240,18 +241,18 @@ func (tx *Tx) CopyFrom(tableName Identifier, columnNames []string, rowSrc CopyFr
 }
 
 // CopyFromReader delegates to the underlying *Conn
-func (tx *Tx) CopyFromReader(r io.Reader, sql string) (commandTag CommandTag, err error) {
+func (tx *Tx) CopyFromReader(r io.Reader, sql string) (commandTag pgconn.CommandTag, err error) {
 	if tx.status != TxStatusInProgress {
-		return CommandTag(""), ErrTxClosed
+		return nil, ErrTxClosed
 	}
 
 	return tx.conn.CopyFromReader(r, sql)
 }
 
 // CopyToWriter delegates to the underlying *Conn
-func (tx *Tx) CopyToWriter(w io.Writer, sql string, args ...interface{}) (commandTag CommandTag, err error) {
+func (tx *Tx) CopyToWriter(w io.Writer, sql string, args ...interface{}) (commandTag pgconn.CommandTag, err error) {
 	if tx.status != TxStatusInProgress {
-		return CommandTag(""), ErrTxClosed
+		return nil, ErrTxClosed
 	}
 
 	return tx.conn.CopyToWriter(w, sql, args...)