diff --git a/src/widgets/newprojectdialog.h b/src/widgets/newprojectdialog.h
--- a/src/widgets/newprojectdialog.h
+++ b/src/widgets/newprojectdialog.h
@@ -55,7 +55,7 @@
     Domain::DataSource::Ptr dataSource() const Q_DECL_OVERRIDE;
 
 private slots:
-    void onNameTextChanged(const QString &text);
+    void onUserInputChanged();
 
 private:
     void applyDefaultSource(const QModelIndex &root);
diff --git a/src/widgets/newprojectdialog.cpp b/src/widgets/newprojectdialog.cpp
--- a/src/widgets/newprojectdialog.cpp
+++ b/src/widgets/newprojectdialog.cpp
@@ -61,14 +61,16 @@
 {
     ui->setupUi(this);
 
-    QObject::connect(ui->nameEdit, &QLineEdit::textChanged, this, &NewProjectDialog::onNameTextChanged);
-    onNameTextChanged(m_name);
+    connect(ui->nameEdit, &QLineEdit::textChanged, this, &NewProjectDialog::onUserInputChanged);
 
     auto taskSourceProxy = new TaskSourceProxy(this);
     taskSourceProxy->setSourceModel(m_flattenProxy);
     ui->sourceCombo->setModel(taskSourceProxy);
-
     m_flattenProxy->setDisplayAncestorData(true);
+    connect(ui->sourceCombo, static_cast<void (QComboBox::*)(int)>(&QComboBox::currentIndexChanged),
+            this, &NewProjectDialog::onUserInputChanged);
+
+    onUserInputChanged();
 }
 
 NewProjectDialog::~NewProjectDialog()
@@ -112,10 +114,15 @@
     return m_source;
 }
 
-void NewProjectDialog::onNameTextChanged(const QString &text)
+void NewProjectDialog::onUserInputChanged()
 {
+    const auto text = ui->nameEdit->text();
+    const auto source = ui->sourceCombo->itemData(ui->sourceCombo->currentIndex(),
+                                                  Presentation::QueryTreeModelBase::ObjectRole)
+                                       .value<Domain::DataSource::Ptr>();
+
     auto buttonOk = ui->buttonBox->button(QDialogButtonBox::Ok);
-    buttonOk->setEnabled(!text.isEmpty());
+    buttonOk->setEnabled(!text.isEmpty() && source);
 }
 
 #include "newprojectdialog.moc"
diff --git a/tests/units/widgets/newprojectdialogtest.cpp b/tests/units/widgets/newprojectdialogtest.cpp
--- a/tests/units/widgets/newprojectdialogtest.cpp
+++ b/tests/units/widgets/newprojectdialogtest.cpp
@@ -57,10 +57,8 @@
             QTest::keyClicks(nameEdit, nameInput);
         }
 
-        if (sourceComboIndex >= 0) {
-            auto sourceCombo = dialog->findChild<QComboBox*>(QStringLiteral("sourceCombo"));
-            sourceCombo->setCurrentIndex(sourceComboIndex);
-        }
+        auto sourceCombo = dialog->findChild<QComboBox*>(QStringLiteral("sourceCombo"));
+        sourceCombo->setCurrentIndex(sourceComboIndex);
 
         auto buttonBox = dialog->findChild<QDialogButtonBox*>(QStringLiteral("buttonBox"));
         if (reject)
@@ -235,6 +233,30 @@
         QCOMPARE(dialog.name(), QString());
         QCOMPARE(dialog.dataSource(), Domain::DataSource::Ptr());
     }
+
+    void shouldNotAllowNoSelectedSource()
+    {
+        // GIVEN
+        Widgets::NewProjectDialog dialog;
+
+        auto sourceModel = createSourceModel();
+        dialog.setDataSourcesModel(sourceModel);
+
+        UserInputSimulator userInput;
+        userInput.dialog = &dialog;
+        userInput.sourceComboIndex = -1;
+        userInput.nameInput = QStringLiteral("name");
+        userInput.reject = true;
+
+        // WHEN
+        userInput.exec();
+
+        // THEN
+        auto buttonOk = dialog.findChild<QDialogButtonBox*>(QStringLiteral("buttonBox"))->button(QDialogButtonBox::Ok);
+        QVERIFY(!buttonOk->isEnabled());
+        QCOMPARE(dialog.name(), QString());
+        QCOMPARE(dialog.dataSource(), Domain::DataSource::Ptr());
+    }
 };
 
 ZANSHIN_TEST_MAIN(NewProjectDialogTest)