diff --git a/libgm/pair_google.go b/libgm/pair_google.go
index 5bc4a73..6aceaeb 100644
--- a/libgm/pair_google.go
+++ b/libgm/pair_google.go
@@ -29,6 +29,7 @@ import (
 	"fmt"
 	"io"
 	"math/big"
+	"strings"
 	"sync"
 	"time"
 
@@ -89,8 +90,11 @@ func (c *Client) signInGaiaGetToken(ctx context.Context) (*gmproto.SignInGaiaRes
 		return nil, err
 	}
 	c.updateTachyonAuthToken(resp.GetTokenData())
-	c.AuthData.Mobile = resp.GetDeviceData().GetDeviceWrapper().GetDevice()
-	c.AuthData.Browser = resp.GetDeviceData().GetDeviceWrapper().GetDevice()
+	device := resp.GetDeviceData().GetDeviceWrapper().GetDevice()
+	lowercaseDevice := proto.Clone(device).(*gmproto.Device)
+	lowercaseDevice.SourceID = strings.ToLower(device.SourceID)
+	c.AuthData.Mobile = lowercaseDevice
+	c.AuthData.Browser = device
 	return resp, nil
 }
 
diff --git a/user.go b/user.go
index 40029a3..69fdd6b 100644
--- a/user.go
+++ b/user.go
@@ -43,6 +43,7 @@ import (
 	"go.mau.fi/mautrix-gmessages/libgm"
 	"go.mau.fi/mautrix-gmessages/libgm/events"
 	"go.mau.fi/mautrix-gmessages/libgm/gmproto"
+	"go.mau.fi/mautrix-gmessages/libgm/util"
 )
 
 type User struct {
@@ -600,6 +601,9 @@ func (user *User) Connect() bool {
 	}
 	user.zlog.Debug().Msg("Connecting to Google Messages")
 	user.BridgeState.Send(status.BridgeState{StateEvent: status.StateConnecting, Error: GMConnecting})
+	if user.Session.Mobile.Network == util.GoogleNetwork {
+		user.Session.Mobile.SourceID = strings.ToLower(user.Session.Mobile.SourceID)
+	}
 	user.createClient(user.Session)
 	err := user.Client.Connect()
 	if err != nil {