diff --git a/app/src/main/java/io/github/wulkanowy/activity/login/LoginTask.java b/app/src/main/java/io/github/wulkanowy/activity/login/LoginTask.java
index fd219e2c..ce72fad9 100644
--- a/app/src/main/java/io/github/wulkanowy/activity/login/LoginTask.java
+++ b/app/src/main/java/io/github/wulkanowy/activity/login/LoginTask.java
@@ -4,10 +4,12 @@ import android.animation.Animator;
 import android.animation.AnimatorListenerAdapter;
 import android.app.Activity;
 import android.content.Context;
+import android.content.DialogInterface;
 import android.content.Intent;
 import android.os.AsyncTask;
 import android.support.design.widget.Snackbar;
 import android.support.design.widget.TextInputLayout;
+import android.support.v7.app.AlertDialog;
 import android.view.View;
 import android.view.inputmethod.InputMethodManager;
 import android.widget.EditText;
@@ -86,6 +88,8 @@ public class LoginTask extends AsyncTask<Void, String, Integer> {
                 return R.string.encrypt_failed_text;
             } catch (NotLoggedInErrorException | IOException e) {
                 return R.string.login_denied_text;
+            } catch (UnsupportedOperationException e) {
+                return -1;
             }
 
             GradeJob gradeJob = new GradeJob();
@@ -135,6 +139,21 @@ public class LoginTask extends AsyncTask<Void, String, Integer> {
                 showSoftKeyboard(symbolView);
                 break;
 
+            // if rooted and SDK < 18
+            case -1:
+                final AlertDialog.Builder alertDialog = new AlertDialog.Builder(activity.get())
+                        .setIcon(android.R.drawable.ic_dialog_alert)
+                        .setTitle(R.string.alert_dialog_blocked_app)
+                        .setMessage(R.string.alert_dialog_blocked_app_message)
+                        .setPositiveButton(R.string.dialog_close, new DialogInterface.OnClickListener() {
+                    @Override
+                    public void onClick(DialogInterface dialogInterface, int i) {
+                        dialogInterface.dismiss();
+                    }
+                });
+                alertDialog.show();
+                break;
+
             default:
                 Snackbar.make(activity.get().findViewById(R.id.coordinatorLayout),
                         messageID, Snackbar.LENGTH_LONG).show();
diff --git a/app/src/main/java/io/github/wulkanowy/security/Safety.java b/app/src/main/java/io/github/wulkanowy/security/Safety.java
index 65f99398..d4969eb7 100644
--- a/app/src/main/java/io/github/wulkanowy/security/Safety.java
+++ b/app/src/main/java/io/github/wulkanowy/security/Safety.java
@@ -3,7 +3,6 @@ package io.github.wulkanowy.security;
 import android.content.Context;
 import android.os.Build;
 import android.util.Base64;
-import android.util.Log;
 
 import io.github.wulkanowy.utilities.RootUtilities;
 
@@ -19,8 +18,7 @@ public class Safety extends Scrambler {
             if (!RootUtilities.isRooted()) {
                 return new String(Base64.encode(plainText.getBytes(), Base64.DEFAULT));
             } else {
-                Log.e(Scrambler.DEBUG_TAG, "Password store in this devices isn't safe because is rooted");
-                throw new UnsupportedOperationException("Password store in this devices isn't safe because is rooted");
+                throw new UnsupportedOperationException("Stored data in this devices isn't safe because android is rooted");
             }
         }
     }
diff --git a/app/src/main/java/io/github/wulkanowy/services/VulcanSynchronization.java b/app/src/main/java/io/github/wulkanowy/services/VulcanSynchronization.java
index 27f25ed0..fcd0dccd 100644
--- a/app/src/main/java/io/github/wulkanowy/services/VulcanSynchronization.java
+++ b/app/src/main/java/io/github/wulkanowy/services/VulcanSynchronization.java
@@ -39,7 +39,8 @@ public class VulcanSynchronization {
     }
 
     public void firstLoginSignInStep(Context context, DaoSession daoSession)
-            throws NotLoggedInErrorException, AccountPermissionException, IOException, CryptoException {
+            throws NotLoggedInErrorException, AccountPermissionException, IOException, CryptoException,
+            UnsupportedOperationException {
         if (firstAccountLogin != null && certificate != null) {
             loginSession = firstAccountLogin.login(context, daoSession, certificate);
         } else {
diff --git a/app/src/main/java/io/github/wulkanowy/services/synchronisation/FirstAccountLogin.java b/app/src/main/java/io/github/wulkanowy/services/synchronisation/FirstAccountLogin.java
index 9b88de4a..e24300f4 100644
--- a/app/src/main/java/io/github/wulkanowy/services/synchronisation/FirstAccountLogin.java
+++ b/app/src/main/java/io/github/wulkanowy/services/synchronisation/FirstAccountLogin.java
@@ -44,7 +44,8 @@ public class FirstAccountLogin {
     }
 
     public LoginSession login(Context context, DaoSession daoSession, String certificate)
-            throws NotLoggedInErrorException, AccountPermissionException, IOException, CryptoException {
+            throws NotLoggedInErrorException, AccountPermissionException, IOException, CryptoException,
+            UnsupportedOperationException {
 
         long userId;
 
diff --git a/app/src/main/res/values-pl/strings.xml b/app/src/main/res/values-pl/strings.xml
index 2df6b575..d287668c 100644
--- a/app/src/main/res/values-pl/strings.xml
+++ b/app/src/main/res/values-pl/strings.xml
@@ -39,10 +39,11 @@
     <string name="fragment_no_grades">Brak ocen</string>
 
     <string name="noInternet_text">Brak połączenia z internetem</string>
-    <string name="root_failed_text">To urządzenie posiada posiada podwyższone uprawnienia (root). Automatyczne logowanie zosatło wyłączone.</string>
     <string name="encrypt_failed_text">Szyfrowanie nie powiodło się. Automatyczne logowanie zostało wyłączone</string>
     <string name="version_text">Wersja %1$s</string>
     <string name="refresh_error_text">"Podczas odświeżania zawartości wystąpił błąd. "</string>
+    <string name="alert_dialog_blocked_app">Blokada aplikacji</string>
+    <string name="alert_dialog_blocked_app_message">W obawie o bezpieczeństwo przechowywanych danych osobistych na urządzeniu z podwyższonymi uprawnieniami (root), aplikacja Wulkanowy została zablokowana</string>
 
     <string name="dialog_description_text">Opis</string>
     <string name="dialog_weight_text">Waga</string>
diff --git a/app/src/main/res/values/strings.xml b/app/src/main/res/values/strings.xml
index 3bf0dd98..a4151ffe 100644
--- a/app/src/main/res/values/strings.xml
+++ b/app/src/main/res/values/strings.xml
@@ -39,10 +39,11 @@
     <string name="fragment_no_grades">No grades</string>
 
     <string name="noInternet_text">No internet connection</string>
-    <string name="root_failed_text">This device is rooted. Automatic login has been disabled</string>
     <string name="encrypt_failed_text">Encryption failed. Automatic login has been disabled</string>
     <string name="version_text">Version %1$s</string>
     <string name="refresh_error_text">An error occurred while refreshing the content.</string>
+    <string name="alert_dialog_blocked_app">Application lock</string>
+    <string name="alert_dialog_blocked_app_message">For the sake of safety of personal data stored on a device with increased authorization (root), the Wulkanowy application has been blocked.</string>
 
     <string name="dialog_description_text">Description</string>
     <string name="dialog_weight_text">Weight</string>