diff --git a/back/methods/imap-time-control/checkInbox.js b/back/methods/imap-time-control/checkInbox.js
index 8cb893c76..6a6b697a7 100644
--- a/back/methods/imap-time-control/checkInbox.js
+++ b/back/methods/imap-time-control/checkInbox.js
@@ -101,7 +101,7 @@ module.exports = Self => {
         const user = await getUser(from);
         let workerMail;
 
-        if (user.id != NULL) {
+        if (user.id != null) {
             workerMail = await Self.app.models.WorkerTimeControlMail.findOne({
                 where: {
                     week: week,
@@ -110,7 +110,7 @@ module.exports = Self => {
                 }
             });
         }
-        if (workerMail != NULL) {
+        if (workerMail != null) {
             await workerMail.updateAttributes({
                 updated: now,
                 state: 'CONFIRMED'
@@ -129,7 +129,7 @@ module.exports = Self => {
         const user = await getUser(from);
         let workerMail;
 
-        if (user.id != NULL) {
+        if (user.id != null) {
             workerMail = await Self.app.models.WorkerTimeControlMail.findOne({
                 where: {
                     week: week,
@@ -138,7 +138,7 @@ module.exports = Self => {
                 }
             });
 
-            if (workerMail != NULL) {
+            if (workerMail != null) {
                 await workerMail.updateAttributes({
                     updated: now,
                     state: 'REVISE',