diff --git a/CMakeLists.txt b/CMakeLists.txt
index 5328fd49d..99b589ab5 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -51,13 +51,15 @@ if (NOT WIN32)
 -Wall \
 -Wcast-align \
 -Wconversion \
--Werror=return-type \
 -Werror=old-style-cast \
+-Werror=return-type \
 -Wextra \
 -Wfloat-equal \
 -Winit-self \
+-Wnon-virtual-dtor \
 -Woverloaded-virtual \
 -Wpointer-arith \
+-Wsign-conversion \
 -Wuninitialized \
 -Wunused \
 ")
diff --git a/src/tests/TestUtils.cpp b/src/tests/TestUtils.cpp
index 1918b8d39..2e1735a7b 100644
--- a/src/tests/TestUtils.cpp
+++ b/src/tests/TestUtils.cpp
@@ -35,7 +35,7 @@
 
 void TestUtils::executeKeySequence (QQuickWindow *window, QKeySequence sequence) {
   for (int i = 0; i < sequence.count(); ++i) {
-    int key = sequence[i];
+    uint key = static_cast<uint>(sequence[static_cast<uint>(i)]);
     QTest::keyClick(
       window,
       Qt::Key(key & ~Qt::KeyboardModifierMask),