diff --git a/src/app/container/calculator.cpp b/src/app/container/calculator.cpp
index 4bd488acb..dc0fafae4 100644
--- a/src/app/container/calculator.cpp
+++ b/src/app/container/calculator.cpp
@@ -164,6 +164,11 @@ void Calculator::InitVariables(const VContainer *data, const QMap<int, QString>
             }
         }
 
+        if (builInFunctions.contains(i.value()))
+        {// We found built-in function
+            found = true;
+        }
+
         if (found == false)
         {
             throw qmu::QmuParserError (ecUNASSIGNABLE_TOKEN, i.value(), formula, i.key());
diff --git a/src/app/container/vcontainer.cpp b/src/app/container/vcontainer.cpp
index 027cf3308..d4a12a768 100644
--- a/src/app/container/vcontainer.cpp
+++ b/src/app/container/vcontainer.cpp
@@ -414,7 +414,7 @@ const QMap<QString, QSharedPointer<VLineAngle> > VContainer::DataAngleLines() co
 //---------------------------------------------------------------------------------------------------------------------
 bool VContainer::IsUnique(const QString &name)
 {
-    return !uniqueNames.contains(name);
+    return (!uniqueNames.contains(name) && !builInFunctions.contains(name));
 }
 
 //---------------------------------------------------------------------------------------------------------------------
diff --git a/src/app/dialogs/app/dialogincrements.cpp b/src/app/dialogs/app/dialogincrements.cpp
index 54c2d40ac..ef575dd10 100644
--- a/src/app/dialogs/app/dialogincrements.cpp
+++ b/src/app/dialogs/app/dialogincrements.cpp
@@ -544,7 +544,7 @@ void DialogIncrements::clickedToolButtonAdd()
     {
         name = QString(tr("Name_%1")).arg(num);
         num++;
-    } while (data->VariableExist(name));
+    } while (data->IsUnique(name)==false);
 
     const quint32 id = data->getNextId();
     const QString description(tr("Description"));
diff --git a/src/app/options.cpp b/src/app/options.cpp
index 95229d42e..02aeae0e1 100644
--- a/src/app/options.cpp
+++ b/src/app/options.cpp
@@ -28,6 +28,7 @@
 
 #include "options.h"
 #include <QString>
+#include <QStringList>
 
 //Same regexp in pattern.xsd shema file. Don't forget synchronize.
 const QString nameRegExp = QStringLiteral("^([^0-9-*/^+=\\s\\(\\)%:;!.,]){1,1}([^-*/^+=\\s\\(\\)%:;!.,]){0,}$");
@@ -212,6 +213,9 @@ const QString max_F   = QStringLiteral("max");
 const QString sum_F   = QStringLiteral("sum");
 const QString avg_F   = QStringLiteral("avg");
 
+const QStringList builInFunctions{sin_F, cos_F, tan_F, asin_F, acos_F, atan_F, sinh_F, cosh_F, tanh_F, asinh_F, acosh_F,
+            atanh_F, log2_F, log10_F, log_F, ln_F, exp_F, sqrt_F, sign_F, rint_F, abs_F, min_F, max_F, sum_F, avg_F};
+
 // Postfix operators
 const QString cm_Oprt = QStringLiteral("cm");
 const QString mm_Oprt = QStringLiteral("mm");
diff --git a/src/app/options.h b/src/app/options.h
index baf82ef35..725c75d4c 100644
--- a/src/app/options.h
+++ b/src/app/options.h
@@ -38,6 +38,7 @@
 #include <QtGlobal>
 
 class QString;
+class QStringList;
 
 static const quint32 null_id = 0;
 
@@ -304,6 +305,8 @@ extern const QString max_F;
 extern const QString sum_F;
 extern const QString avg_F;
 
+extern const QStringList builInFunctions;
+
 // Postfix operators
 extern const QString cm_Oprt;
 extern const QString mm_Oprt;
diff --git a/src/app/widgets/textdelegate.cpp b/src/app/widgets/textdelegate.cpp
index c037fbbfd..296dd1507 100644
--- a/src/app/widgets/textdelegate.cpp
+++ b/src/app/widgets/textdelegate.cpp
@@ -79,7 +79,7 @@ void TextDelegate::setEditorData(QWidget *editor, const QModelIndex &index) cons
     SCASSERT(lineEdit != nullptr);
     if ( lastText != text && text.isEmpty() == false)
     {
-        //Here need save text, but method is const, so, we use signal instead.
+        //Here need save text, but this method is const, so, we use signal instead.
         emit SaveText(text);
     }
     lineEdit->setText(text);
@@ -129,7 +129,7 @@ void TextDelegate::commitAndCloseEditor()
     QLineEdit *lineEdit = qobject_cast<QLineEdit*>(sender());
     SCASSERT(lineEdit != nullptr);
     QString text = lineEdit->text();
-    if ( lastText != text && text.isEmpty() == false && data->VariableExist(text) == false)
+    if ( lastText != text && text.isEmpty() == false && data->IsUnique(text))
     {
         lastText = text;
         emit commitData(lineEdit);
diff --git a/src/app/widgets/textdelegate.h b/src/app/widgets/textdelegate.h
index 0b2138b40..974579ed7 100644
--- a/src/app/widgets/textdelegate.h
+++ b/src/app/widgets/textdelegate.h
@@ -53,6 +53,7 @@ signals:
     void    SaveText(const QString &text) const;
 public slots:
     void    commitAndCloseEditor();
+private slots:
     void    InitText(const QString &text);
 private:
     Q_DISABLE_COPY(TextDelegate)