diff --git a/src/plugins/qmldesigner/designercore/model/abstractproperty.cpp b/src/plugins/qmldesigner/designercore/model/abstractproperty.cpp
index 1eab05a080c..fa54d60a898 100644
--- a/src/plugins/qmldesigner/designercore/model/abstractproperty.cpp
+++ b/src/plugins/qmldesigner/designercore/model/abstractproperty.cpp
@@ -58,6 +58,7 @@ AbstractProperty::AbstractProperty(const PropertyName &propertyName, const Inter
     m_view(view)
 {
     Q_ASSERT(!m_model || m_view);
+    Q_ASSERT_X(!m_propertyName.contains(' '), Q_FUNC_INFO, "a property name can not contain a space");
 }
 
 AbstractProperty::AbstractProperty(const Internal::InternalPropertyPointer &property, Model* model,  AbstractView *view)
diff --git a/src/plugins/qmldesigner/qmldesignerextension/connectioneditor/delegates.cpp b/src/plugins/qmldesigner/qmldesignerextension/connectioneditor/delegates.cpp
index 7fe68882eb7..81a6a09d58d 100644
--- a/src/plugins/qmldesigner/qmldesignerextension/connectioneditor/delegates.cpp
+++ b/src/plugins/qmldesigner/qmldesignerextension/connectioneditor/delegates.cpp
@@ -59,6 +59,7 @@ PropertiesComboBox::PropertiesComboBox(QWidget *parent) : QComboBox(parent)
 {
     static QScopedPointer<QStyle> style(QStyleFactory::create(QLatin1String("windows")));
     setEditable(true);
+    setValidator(new QRegularExpressionValidator(QRegularExpression(QLatin1String("[a-z|A-Z|0-9|._-]*")), this));
     if (style)
         setStyle(style.data());
 }