diff --git a/server/core_authenticate.go b/server/core_authenticate.go
index 67cd418dacb226667cbd0959a6a42af98be67404..687a027922d861dddb5e20ac49ea0eeda26e932f 100644
--- a/server/core_authenticate.go
+++ b/server/core_authenticate.go
@@ -231,11 +231,12 @@ WHERE NOT EXISTS
 
 		result, err := tx.ExecContext(ctx, query, userID, username, deviceID)
 		if err != nil {
-			if err == sql.ErrNoRows {
+			e, ok := err.(pgx.PgError)
+			if err == sql.ErrNoRows || (ok && e.Code == dbErrorUniqueViolation && strings.Contains(e.Message, "user_device_pkey")) {
 				// A concurrent write has inserted this device ID.
 				logger.Info("Did not insert new user as device ID already exists.", zap.Error(err), zap.String("deviceID", deviceID), zap.String("username", username), zap.Bool("create", create))
 				return StatusError(codes.Internal, "Error finding or creating user account.", err)
-			} else if e, ok := err.(pgx.PgError); ok && e.Code == dbErrorUniqueViolation && strings.Contains(e.Message, "users_username_key") {
+			} else if ok && e.Code == dbErrorUniqueViolation && strings.Contains(e.Message, "users_username_key") {
 				return StatusError(codes.AlreadyExists, "Username is already in use.", err)
 			}
 			logger.Debug("Cannot find or create user with device ID.", zap.Error(err), zap.String("deviceID", deviceID), zap.String("username", username), zap.Bool("create", create))