diff --git a/bridgev2/networkinterface.go b/bridgev2/networkinterface.go
index 31647f63..bf2d60ee 100644
--- a/bridgev2/networkinterface.go
+++ b/bridgev2/networkinterface.go
@@ -817,7 +817,8 @@ type GroupFieldCapability struct {
 type GroupCreateParams struct {
 	Type string `json:"type,omitempty"`
 
-	Username     string               `json:"username,omitempty"`
+	Username string `json:"username,omitempty"`
+	// Clients may also provide MXIDs here, but provisionutil will normalize them, so bridges only need to handle network IDs
 	Participants []networkid.UserID   `json:"participants,omitempty"`
 	Parent       *networkid.PortalKey `json:"parent,omitempty"`
 
diff --git a/bridgev2/provisionutil/creategroup.go b/bridgev2/provisionutil/creategroup.go
index f389ab42..acae9360 100644
--- a/bridgev2/provisionutil/creategroup.go
+++ b/bridgev2/provisionutil/creategroup.go
@@ -38,7 +38,12 @@ func CreateGroup(ctx context.Context, login *bridgev2.UserLogin, params *bridgev
 		return nil, bridgev2.RespError(mautrix.MInvalidParam.WithMessage("Must have at least %d members", typeSpec.Participants.MinLength))
 	}
 	userIDValidatingNetwork, uidValOK := login.Bridge.Network.(bridgev2.IdentifierValidatingNetwork)
-	for _, participant := range params.Participants {
+	for i, participant := range params.Participants {
+		parsedParticipant, ok := login.Bridge.Matrix.ParseGhostMXID(id.UserID(participant))
+		if ok {
+			participant = parsedParticipant
+			params.Participants[i] = participant
+		}
 		if uidValOK && !userIDValidatingNetwork.ValidateUserID(participant) {
 			return nil, bridgev2.RespError(mautrix.MInvalidParam.WithMessage("User ID %q is not valid on this network", participant))
 		}