diff --git a/src/CMakeLists.txt b/src/CMakeLists.txt
index 63c250373..762d6c2c5 100644
--- a/src/CMakeLists.txt
+++ b/src/CMakeLists.txt
@@ -100,7 +100,7 @@ set(SOURCES "main.cpp" "imagewriter.cpp" "networkaccessmanagerfactory.cpp"
     "devicewrapper.cpp" "devicewrapperblockcacheentry.cpp" "devicewrapperpartition.cpp" "devicewrapperfatpartition.cpp"
     "driveformatthread.cpp" "localfileextractthread.cpp" "powersaveblocker.cpp" "downloadstatstelemetry.cpp" "qml.qrc" "dependencies/sha256crypt/sha256crypt.c" "cli.cpp")
 
-find_package(Qt5 COMPONENTS Core Quick LinguistTools Svg OPTIONAL_COMPONENTS Widgets)
+find_package(Qt5 5.14 COMPONENTS Core Quick LinguistTools Svg OPTIONAL_COMPONENTS Widgets)
 if (Qt5Widgets_FOUND)
     set(EXTRALIBS ${EXTRALIBS} Qt5::Widgets)
 endif()
diff --git a/src/OptionsPopup.qml b/src/OptionsPopup.qml
index da0272d86..a1f855e61 100644
--- a/src/OptionsPopup.qml
+++ b/src/OptionsPopup.qml
@@ -3,7 +3,7 @@
  * Copyright (C) 2021 Raspberry Pi Ltd
  */
 
-import QtQuick 2.9
+import QtQuick 2.15
 import QtQuick.Controls 2.2
 import QtQuick.Layouts 1.0
 import QtQuick.Controls.Material 2.2
@@ -128,9 +128,7 @@ Popup {
                             id: fieldHostname
                             enabled: chkHostname.checked
                             text: "raspberrypi"
-                            /* FIXME: use RegularExpressionValidator instead when moving to newer Qt version.
-                               It is not available in 5.12 that is still being used by Ubuntu 20 LTS though */
-                            validator: RegExpValidator { regExp: /[0-9A-Za-z][0-9A-Za-z-]{0,62}/ }
+                            validator: RegularExpressionValidator { regularExpression: /[0-9A-Za-z][0-9A-Za-z-]{0,62}/ }
                         }
                         Text {
                             text : ".local"
diff --git a/src/devicewrapperfatpartition.cpp b/src/devicewrapperfatpartition.cpp
index a05d2c450..5b566c421 100644
--- a/src/devicewrapperfatpartition.cpp
+++ b/src/devicewrapperfatpartition.cpp
@@ -1,6 +1,5 @@
 #include "devicewrapperfatpartition.h"
 #include "devicewrapperstructs.h"
-#include "qdebug.h"
 
 /*
  * SPDX-License-Identifier: Apache-2.0
@@ -314,7 +313,7 @@ void DeviceWrapperFatPartition::writeFile(const QString &filename, const QByteAr
     for (uint32_t cluster : qAsConst(clusterList))
     {
         seekCluster(cluster);
-        write(contents.data()+pos, qMin(_bytesPerCluster, contents.length()-pos));
+        write(contents.data()+pos, qMin((qsizetype)_bytesPerCluster, (qsizetype)(contents.length()-pos)));
 
         pos += _bytesPerCluster;
         if (pos >= contents.length())