diff --git a/pgconn.go b/pgconn.go
index db741d47..7ddc50e6 100644
--- a/pgconn.go
+++ b/pgconn.go
@@ -712,53 +712,16 @@ func (pgConn *PgConn) Exec(ctx context.Context, sql string) *MultiResultReader {
 //
 // ResultReader must be closed before PgConn can be used again.
 func (pgConn *PgConn) ExecParams(ctx context.Context, sql string, paramValues [][]byte, paramOIDs []uint32, paramFormats []int16, resultFormats []int16) *ResultReader {
-	result := &ResultReader{
-		pgConn:                 pgConn,
-		ctx:                    ctx,
-		cleanupContextDeadline: func() {},
-	}
-
-	if err := pgConn.lock(); err != nil {
-		result.concludeCommand("", err)
-		result.closed = true
+	result := pgConn.execExtendedPrefix(ctx, paramValues)
+	if result.closed {
 		return result
 	}
 
-	if len(paramValues) > math.MaxUint16 {
-		result.concludeCommand("", fmt.Errorf("extended protocol limited to %v parameters", math.MaxUint16))
-		result.closed = true
-		pgConn.unlock()
-		return result
-	}
-
-	select {
-	case <-ctx.Done():
-		result.concludeCommand("", ctx.Err())
-		result.closed = true
-		pgConn.unlock()
-		return result
-	default:
-	}
-	result.cleanupContextDeadline = contextDoneToConnDeadline(ctx, pgConn.conn)
-
 	var buf []byte
-
-	// TODO - refactor ExecParams and ExecPrepared - these lines only difference
 	buf = (&pgproto3.Parse{Query: sql, ParameterOIDs: paramOIDs}).Encode(buf)
 	buf = (&pgproto3.Bind{ParameterFormatCodes: paramFormats, Parameters: paramValues, ResultFormatCodes: resultFormats}).Encode(buf)
 
-	buf = (&pgproto3.Describe{ObjectType: 'P'}).Encode(buf)
-	buf = (&pgproto3.Execute{}).Encode(buf)
-	buf = (&pgproto3.Sync{}).Encode(buf)
-
-	_, err := pgConn.conn.Write(buf)
-	if err != nil {
-		pgConn.hardClose()
-		result.concludeCommand("", err)
-		result.cleanupContextDeadline()
-		result.closed = true
-		pgConn.unlock()
-	}
+	pgConn.execExtendedSuffix(buf, result)
 
 	return result
 }
@@ -776,6 +739,20 @@ func (pgConn *PgConn) ExecParams(ctx context.Context, sql string, paramValues []
 //
 // ResultReader must be closed before PgConn can be used again.
 func (pgConn *PgConn) ExecPrepared(ctx context.Context, stmtName string, paramValues [][]byte, paramFormats []int16, resultFormats []int16) *ResultReader {
+	result := pgConn.execExtendedPrefix(ctx, paramValues)
+	if result.closed {
+		return result
+	}
+
+	var buf []byte
+	buf = (&pgproto3.Bind{PreparedStatement: stmtName, ParameterFormatCodes: paramFormats, Parameters: paramValues, ResultFormatCodes: resultFormats}).Encode(buf)
+
+	pgConn.execExtendedSuffix(buf, result)
+
+	return result
+}
+
+func (pgConn *PgConn) execExtendedPrefix(ctx context.Context, paramValues [][]byte) *ResultReader {
 	result := &ResultReader{
 		pgConn:                 pgConn,
 		ctx:                    ctx,
@@ -805,8 +782,10 @@ func (pgConn *PgConn) ExecPrepared(ctx context.Context, stmtName string, paramVa
 	}
 	result.cleanupContextDeadline = contextDoneToConnDeadline(ctx, pgConn.conn)
 
-	var buf []byte
-	buf = (&pgproto3.Bind{PreparedStatement: stmtName, ParameterFormatCodes: paramFormats, Parameters: paramValues, ResultFormatCodes: resultFormats}).Encode(buf)
+	return result
+}
+
+func (pgConn *PgConn) execExtendedSuffix(buf []byte, result *ResultReader) {
 	buf = (&pgproto3.Describe{ObjectType: 'P'}).Encode(buf)
 	buf = (&pgproto3.Execute{}).Encode(buf)
 	buf = (&pgproto3.Sync{}).Encode(buf)
@@ -819,8 +798,6 @@ func (pgConn *PgConn) ExecPrepared(ctx context.Context, stmtName string, paramVa
 		result.closed = true
 		pgConn.unlock()
 	}
-
-	return result
 }
 
 // CopyTo executes the copy command sql and copies the results to w.