diff --git a/source/ubl-settings-datetime.cc b/source/ubl-settings-datetime.cc
index 841fbe8..882c9f5 100644
--- a/source/ubl-settings-datetime.cc
+++ b/source/ubl-settings-datetime.cc
@@ -893,10 +893,38 @@ vector<int> MainWindow::find_all(string &str_ntp, string substr) {
     return sub_index;
 }
 
+bool MainWindow::check_num_ntp(string &str_ntp) {
+    int code_ascii = 0;
+    bool flag_is_num = false;
+    for (size_t index = 0; index < str_ntp.length(); index++) {
+        code_ascii = static_cast<int>(str_ntp[index]);
+        if (code_ascii >= 48 && code_ascii <= 57 ) {
+            flag_is_num = true;
+            break;
+        }
+    }
+    return flag_is_num;
+}
+
+bool MainWindow::check_string_ntp(string &str_ntp) {
+    int code_ascii = 0;
+    bool flag_is_str = false;
+    for (size_t index = 0; index < str_ntp.length(); index++) {
+        code_ascii = static_cast<int>(str_ntp[index]);
+        if ((code_ascii >= 65 && code_ascii <= 90) || (code_ascii >= 97 && code_ascii <= 122)) {
+            flag_is_str = true;
+            break;
+        }
+    }
+    return flag_is_str;
+}
+
 bool MainWindow::check_ntp(string &str_ntp) {
+    bool flag_is_num = this->check_num_ntp(str_ntp);
+    bool flag_is_str = this->check_string_ntp(str_ntp);
     vector<int> sub_index = this->find_all(str_ntp, ".");
-    if (sub_index.size() == 1) {
-        int index_point = sub_index[0];
+    if (sub_index.size() != 0 && flag_is_str) {
+        int index_point = sub_index[sub_index.size()-1];
         int len_str_ntp = str_ntp.length();
         if (((len_str_ntp-index_point) >= 2) && (index_point > 2)) {
             return false;
@@ -905,7 +933,7 @@ bool MainWindow::check_ntp(string &str_ntp) {
             return true;
         }
     }
-    else if (sub_index.size() == 3) {
+    else if (sub_index.size() == 3 && (flag_is_num && flag_is_str == false)) {
         int index_str_ntp = sub_index[0];
         int index_str_ntp_1 = sub_index[1];
         int index_str_ntp_2 = sub_index[2];
diff --git a/source/ubl-settings-datetime.h b/source/ubl-settings-datetime.h
index aa8322b..974a814 100644
--- a/source/ubl-settings-datetime.h
+++ b/source/ubl-settings-datetime.h
@@ -309,6 +309,8 @@ class MainWindow : public Gtk::ApplicationWindow {
         void settings();
         void flag_block_gui();
         void add_CSS();
+        bool check_string_ntp(string &str_ntp);
+        bool check_num_ntp(string &str_ntp);
         void get_builder();
         void event();
         void gui_mess_close();