diff --git a/src/Gui/DlgExpressionInput.cpp b/src/Gui/DlgExpressionInput.cpp
index a5bc87eed..99641c2dc 100644
--- a/src/Gui/DlgExpressionInput.cpp
+++ b/src/Gui/DlgExpressionInput.cpp
@@ -35,7 +35,6 @@ using namespace App;
 using namespace Gui::Dialog;
 
 const int DlgExpressionInput::h = 15;
-const int DlgExpressionInput::l = 30;
 const int DlgExpressionInput::r = 30;
 const int DlgExpressionInput::d = 7;
 
@@ -45,7 +44,8 @@ DlgExpressionInput::DlgExpressionInput(const App::ObjectIdentifier & _path, boos
     expression(_expression ? _expression->copy() : 0),
     path(_path),
     discarded(false),
-    impliedUnit(_impliedUnit)
+    impliedUnit(_impliedUnit),
+    l(30)
 {
     assert(path.getDocumentObject() != 0);
 
@@ -91,6 +91,19 @@ QPoint DlgExpressionInput::tip() const
     return QPoint(l - d, 0);
 }
 
+void DlgExpressionInput::setGeometry(int x, int y, int w, int h)
+{
+    QDesktopWidget widget;
+    int screenWidth = widget.availableGeometry(widget.primaryScreen()).width();
+
+    if (x + w > screenWidth) {
+        l = l + (x + w - screenWidth);
+        x = screenWidth - w - 10;
+    }
+
+    QWidget::setGeometry(x, y, w, h);
+}
+
 void DlgExpressionInput::paintEvent(QPaintEvent * event) {
     QPainter painter(this);
     QPainterPath path;
diff --git a/src/Gui/DlgExpressionInput.h b/src/Gui/DlgExpressionInput.h
index dd985d836..ba1d80b48 100644
--- a/src/Gui/DlgExpressionInput.h
+++ b/src/Gui/DlgExpressionInput.h
@@ -62,6 +62,8 @@ public:
 
     QPoint tip() const;
 
+    void setGeometry(int x, int y, int w, int h);
+
 private Q_SLOTS:
     void textChanged(const QString & text);
     void setDiscarded();
@@ -74,7 +76,7 @@ private:
     const Base::Unit impliedUnit;
 
     static const int h;
-    static const int l;
+    int l;
     static const int r;
     static const int d;
 };
diff --git a/src/Gui/QuantitySpinBox.cpp b/src/Gui/QuantitySpinBox.cpp
index 5f42030cd..e0d8d583f 100644
--- a/src/Gui/QuantitySpinBox.cpp
+++ b/src/Gui/QuantitySpinBox.cpp
@@ -497,7 +497,7 @@ void QuantitySpinBox::openFormulaDialog()
     Gui::Dialog::DlgExpressionInput box(getPath(), getExpression(), d->unit, this);
 
     QPoint pos = mapToGlobal(QPoint(width() / 2, height() / 2));
-    box.setGeometry(pos.x() - box.tip().x(), pos.y() - box.tip().y(), width(), height());
+    box.setGeometry(pos.x() - box.tip().x(), pos.y() - box.tip().y(), box.width(), box.height());
     if (box.exec() == QDialog::Accepted)
         setExpression(box.getExpression());
     else if (box.discardedFormula())