diff --git a/app/src/main/java/com/beemdevelopment/aegis/Preferences.java b/app/src/main/java/com/beemdevelopment/aegis/Preferences.java
index de37bb81..73f1e619 100644
--- a/app/src/main/java/com/beemdevelopment/aegis/Preferences.java
+++ b/app/src/main/java/com/beemdevelopment/aegis/Preferences.java
@@ -159,4 +159,12 @@ public class Preferences {
     public void setBackupsVersionCount(int versions) {
         _prefs.edit().putInt("pref_backups_versions", versions).apply();
     }
+
+    public boolean isTimeSyncWarningEnabled() {
+        return _prefs.getBoolean("pref_warn_time_sync", true);
+    }
+
+    public void setIsTimeSyncWarningEnabled(boolean enabled) {
+        _prefs.edit().putBoolean("pref_warn_time_sync", enabled).apply();
+    }
 }
diff --git a/app/src/main/java/com/beemdevelopment/aegis/ui/Dialogs.java b/app/src/main/java/com/beemdevelopment/aegis/ui/Dialogs.java
index d9998840..16978e85 100644
--- a/app/src/main/java/com/beemdevelopment/aegis/ui/Dialogs.java
+++ b/app/src/main/java/com/beemdevelopment/aegis/ui/Dialogs.java
@@ -6,6 +6,8 @@ import android.content.ClipData;
 import android.content.ClipboardManager;
 import android.content.Context;
 import android.content.DialogInterface;
+import android.content.Intent;
+import android.provider.Settings;
 import android.text.Editable;
 import android.text.InputType;
 import android.text.TextWatcher;
@@ -293,6 +295,31 @@ public class Dialogs {
         Dialogs.showSecureDialog(dialog);
     }
 
+    public static void showTimeSyncWarningDialog(Context context, Dialog.OnClickListener listener) {
+        Preferences prefs = new Preferences(context);
+        View view = LayoutInflater.from(context).inflate(R.layout.dialog_time_sync, null);
+        CheckBox checkBox = view.findViewById(R.id.check_warning_disable);
+
+        showSecureDialog(new AlertDialog.Builder(context)
+                .setTitle(R.string.time_sync_warning_title)
+                .setView(view)
+                .setCancelable(false)
+                .setPositiveButton(R.string.yes, (dialog, which) -> {
+                    if (checkBox.isChecked()) {
+                        prefs.setIsTimeSyncWarningEnabled(false);
+                    }
+                    if (listener != null) {
+                        listener.onClick(dialog, which);
+                    }
+                })
+                .setNegativeButton(R.string.no, (dialog, which) -> {
+                    if (checkBox.isChecked()) {
+                        prefs.setIsTimeSyncWarningEnabled(false);
+                    }
+                })
+                .create());
+    }
+
     public interface NumberInputListener {
         void onNumberInputResult(int number);
     }
diff --git a/app/src/main/java/com/beemdevelopment/aegis/ui/MainActivity.java b/app/src/main/java/com/beemdevelopment/aegis/ui/MainActivity.java
index 2c4f14eb..8b70f4b9 100644
--- a/app/src/main/java/com/beemdevelopment/aegis/ui/MainActivity.java
+++ b/app/src/main/java/com/beemdevelopment/aegis/ui/MainActivity.java
@@ -10,6 +10,7 @@ import android.graphics.BitmapFactory;
 import android.graphics.Rect;
 import android.net.Uri;
 import android.os.Bundle;
+import android.provider.Settings;
 import android.view.Menu;
 import android.view.MenuInflater;
 import android.view.MenuItem;
@@ -343,11 +344,23 @@ public class MainActivity extends AegisActivity implements EntryListView.Listene
     private void onDoIntroResult() {
         _vault = _app.getVaultManager();
         loadEntries();
+        checkTimeSyncSetting();
+    }
+
+    private void checkTimeSyncSetting() {
+        boolean autoTime = Settings.Global.getInt(getContentResolver(), Settings.Global.AUTO_TIME, 1) == 1;
+        if (!autoTime && getPreferences().isTimeSyncWarningEnabled()) {
+            Dialogs.showTimeSyncWarningDialog(this, (dialog, which) -> {
+                Intent intent = new Intent(Settings.ACTION_DATE_SETTINGS);
+                startActivity(intent);
+            });
+        }
     }
 
     private void onDecryptResult() {
         _vault = _app.getVaultManager();
         loadEntries();
+        checkTimeSyncSetting();
     }
 
     private void startScanActivity() {
@@ -450,6 +463,7 @@ public class MainActivity extends AegisActivity implements EntryListView.Listene
             _entryListView.refresh(false);
         } else {
             loadEntries();
+            checkTimeSyncSetting();
         }
 
         handleDeeplink();
diff --git a/app/src/main/res/layout/dialog_time_sync.xml b/app/src/main/res/layout/dialog_time_sync.xml
new file mode 100644
index 00000000..49f42838
--- /dev/null
+++ b/app/src/main/res/layout/dialog_time_sync.xml
@@ -0,0 +1,22 @@
+<?xml version="1.0" encoding="utf-8"?>
+<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
+    android:orientation="vertical"
+    android:layout_width="match_parent"
+    android:layout_height="match_parent"
+    android:paddingBottom="10dp"
+    android:paddingTop="10dp">
+    <TextView
+        android:layout_marginStart="25dp"
+        android:layout_marginEnd="25dp"
+        android:layout_width="match_parent"
+        android:layout_height="wrap_content"
+        android:text="@string/time_sync_warning_message"/>
+    <CheckBox
+        android:id="@+id/check_warning_disable"
+        android:layout_marginStart="20dp"
+        android:layout_marginEnd="20dp"
+        android:layout_width="match_parent"
+        android:layout_height="wrap_content"
+        android:layout_marginTop="10dp"
+        android:text="@string/time_sync_warning_disable"/>
+</LinearLayout>
diff --git a/app/src/main/res/values/strings.xml b/app/src/main/res/values/strings.xml
index 7e9207e0..047eaaa4 100644
--- a/app/src/main/res/values/strings.xml
+++ b/app/src/main/res/values/strings.xml
@@ -231,6 +231,9 @@
     <string name="support_rate_description">Support us by leaving a review in the Google Play Store</string>
     <string name="webview_error">This device doesn\'t support web view, which is necessary to view the changelog. It is missing a system component.</string>
     <string name="email">Email</string>
+    <string name="time_sync_warning_title">Automatic time synchronization</string>
+    <string name="time_sync_warning_message">Aegis relies on the system time to be in sync to generate correct codes. A deviation of only a few seconds could result in incorrect codes. It looks like your device is not configured to automatically synchronize the time. Would you like to do so now?</string>
+    <string name="time_sync_warning_disable">Stop warning me. I know what I\'m doing.</string>
 
     <string name="custom_notices_format_style" translatable="false" >
         body {