diff --git a/downstream.go b/downstream.go
index a008c0d..58a3f2f 100644
--- a/downstream.go
+++ b/downstream.go
@@ -1007,7 +1007,7 @@ func (dc *downstreamConn) handleAuthenticateCommand(msg *irc.Message) (result *d
 
 		dc.sasl.pendingResp.WriteString(chunk)
 
-		if len(chunk) == maxSASLLength {
+		if len(chunk) == xirc.MaxSASLLength {
 			return nil, nil // Multi-line response, wait for the next command
 		}
 
diff --git a/irc.go b/irc.go
index fc4ee11..9ae5d4e 100644
--- a/irc.go
+++ b/irc.go
@@ -15,8 +15,6 @@ import (
 
 // TODO: generalize and move helpers to the xirc package
 
-const maxSASLLength = 400
-
 type userModes string
 
 func (ms userModes) Has(c byte) bool {
diff --git a/upstream.go b/upstream.go
index c474083..59cbfba 100644
--- a/upstream.go
+++ b/upstream.go
@@ -641,25 +641,8 @@ func (uc *upstreamConn) handleMessage(ctx context.Context, msg *irc.Message) err
 			return err
 		}
 
-		// <= instead of < because we need to send a final empty response if
-		// the last chunk is exactly 400 bytes long
-		for i := 0; i <= len(resp); i += maxSASLLength {
-			j := i + maxSASLLength
-			if j > len(resp) {
-				j = len(resp)
-			}
-
-			chunk := resp[i:j]
-
-			var respStr = "+"
-			if len(chunk) != 0 {
-				respStr = base64.StdEncoding.EncodeToString(chunk)
-			}
-
-			uc.SendMessage(ctx, &irc.Message{
-				Command: "AUTHENTICATE",
-				Params:  []string{respStr},
-			})
+		for _, msg := range xirc.GenerateSASL(resp) {
+			uc.SendMessage(ctx, msg)
 		}
 	case irc.RPL_LOGGEDIN:
 		var rawPrefix string
diff --git a/xirc/genmsg.go b/xirc/genmsg.go
index a4abc1c..e796e9a 100644
--- a/xirc/genmsg.go
+++ b/xirc/genmsg.go
@@ -1,6 +1,7 @@
 package xirc
 
 import (
+	"encoding/base64"
 	"fmt"
 	"sort"
 	"strings"
@@ -211,3 +212,28 @@ func GenerateNamesReply(prefix *irc.Prefix, nick string, channel string, status
 	})
 	return msgs
 }
+
+func GenerateSASL(resp []byte) []*irc.Message {
+	// <= instead of < because we need to send a final empty response if
+	// the last chunk is exactly 400 bytes long
+	var msgs []*irc.Message
+	for i := 0; i <= len(resp); i += MaxSASLLength {
+		j := i + MaxSASLLength
+		if j > len(resp) {
+			j = len(resp)
+		}
+
+		chunk := resp[i:j]
+
+		var respStr = "+"
+		if len(chunk) != 0 {
+			respStr = base64.StdEncoding.EncodeToString(chunk)
+		}
+
+		msgs = append(msgs, &irc.Message{
+			Command: "AUTHENTICATE",
+			Params:  []string{respStr},
+		})
+	}
+	return msgs
+}
diff --git a/xirc/xirc.go b/xirc/xirc.go
index 0a9ac33..f321071 100644
--- a/xirc/xirc.go
+++ b/xirc/xirc.go
@@ -14,6 +14,8 @@ const (
 	maxMessageParams = 15
 )
 
+const MaxSASLLength = 400
+
 const (
 	RPL_STATSPING     = "246"
 	RPL_LOCALUSERS    = "265"