diff --git a/src/libs/qmleditorwidgets/easingpane/easingcontextpane.h b/src/libs/qmleditorwidgets/easingpane/easingcontextpane.h
index 570de97fd7a..b1690a79810 100644
--- a/src/libs/qmleditorwidgets/easingpane/easingcontextpane.h
+++ b/src/libs/qmleditorwidgets/easingpane/easingcontextpane.h
@@ -12,10 +12,10 @@ class QSpinBox;
 class QDoubleSpinBox;
 class QGraphicsView;
 class QVariant;
-QT_END_NAMESPACE
-
 class EasingGraph;
 
+QT_END_NAMESPACE
+
 namespace QmlJS { class PropertyReader; }
 
 namespace QmlEditorWidgets {
diff --git a/src/libs/qmljs/parser/qmljslexer_p.h b/src/libs/qmljs/parser/qmljslexer_p.h
index 1d2195369ad..9182f2ead88 100644
--- a/src/libs/qmljs/parser/qmljslexer_p.h
+++ b/src/libs/qmljs/parser/qmljslexer_p.h
@@ -20,9 +20,11 @@
 #include <QtCore/qstring.h>
 #include <QtCore/qstack.h>
 
-QT_QML_BEGIN_NAMESPACE
-
+QT_BEGIN_NAMESPACE
 class QDebug;
+QT_END_NAMESPACE
+
+QT_QML_BEGIN_NAMESPACE
 
 namespace QmlJS {
 
diff --git a/src/libs/utils/mimetypes2/mimetype.cpp b/src/libs/utils/mimetypes2/mimetype.cpp
index eadfb9e53c7..926ca6d950f 100644
--- a/src/libs/utils/mimetypes2/mimetype.cpp
+++ b/src/libs/utils/mimetypes2/mimetype.cpp
@@ -516,9 +516,6 @@ void MimeType::setPreferredSuffix(const QString &suffix)
     d->globPatterns.prepend(QLatin1String("*.") + suffix);
 }
 
-} // namespace Utils
-
-#ifndef QT_NO_DEBUG_STREAM
 QDebug operator<<(QDebug debug, const Utils::MimeType &mime)
 {
     QDebugStateSaver saver(debug);
@@ -529,6 +526,8 @@ QDebug operator<<(QDebug debug, const Utils::MimeType &mime)
     }
     return debug;
 }
-#endif
+
+} // namespace Utils
+
 
 #include "moc_mimetype.cpp"
diff --git a/src/libs/utils/mimetypes2/mimetype.h b/src/libs/utils/mimetypes2/mimetype.h
index 52587ff3aa4..ec28140d6ae 100644
--- a/src/libs/utils/mimetypes2/mimetype.h
+++ b/src/libs/utils/mimetypes2/mimetype.h
@@ -11,13 +11,15 @@
 #include <QtCore/qstring.h>
 #include <QtCore/qstringlist.h>
 
+QT_BEGIN_NAMESPACE
+class QDebug;
+QT_END_NAMESPACE
+
 namespace Utils {
 
 class MimeTypePrivate;
 class MimeType;
 
-QTCREATOR_UTILS_EXPORT size_t qHash(const MimeType &key, size_t seed = 0) noexcept;
-
 class QTCREATOR_UTILS_EXPORT MimeType
 {
     Q_GADGET
@@ -89,18 +91,13 @@ protected:
     friend class MimeBinaryProvider;
     friend class MimeTypePrivate;
     friend QTCREATOR_UTILS_EXPORT size_t qHash(const MimeType &key, size_t seed) noexcept;
+    friend QTCREATOR_UTILS_EXPORT QDebug operator<<(QDebug debug, const MimeType &mime);
 
     QExplicitlySharedDataPointer<MimeTypePrivate> d;
 };
 
-
 } // namespace Utils
 
 QT_BEGIN_NAMESPACE
-#ifndef QT_NO_DEBUG_STREAM
-class QDebug;
-QTCREATOR_UTILS_EXPORT QDebug operator<<(QDebug debug, const Utils::MimeType &mime);
-#endif
-
 Q_DECLARE_SHARED(Utils::MimeType)
 QT_END_NAMESPACE
diff --git a/src/plugins/qmldesigner/components/componentcore/qmleditormenu.h b/src/plugins/qmldesigner/components/componentcore/qmleditormenu.h
index 4163fccbead..2b7ecb386b9 100644
--- a/src/plugins/qmldesigner/components/componentcore/qmleditormenu.h
+++ b/src/plugins/qmldesigner/components/componentcore/qmleditormenu.h
@@ -5,7 +5,9 @@
 
 #include <QMenu>
 
+QT_BEGIN_NAMESPACE
 class QStyleOptionMenuItem;
+QT_END_NAMESPACE
 
 namespace QmlDesigner {
 
diff --git a/src/plugins/qmldesigner/components/edit3d/edit3dactions.h b/src/plugins/qmldesigner/components/edit3d/edit3dactions.h
index 4e8be202b9f..4cf1ab837d8 100644
--- a/src/plugins/qmldesigner/components/edit3d/edit3dactions.h
+++ b/src/plugins/qmldesigner/components/edit3d/edit3dactions.h
@@ -8,7 +8,10 @@
 #include <QWidgetAction>
 #include <QIcon>
 
+QT_BEGIN_NAMESPACE
 class QWidgetAction;
+QT_END_NAMESPACE
+
 namespace QmlDesigner {
 
 using SelectionContextOperation = std::function<void(const SelectionContext &)>;
diff --git a/src/plugins/terminal/shortcutmap.h b/src/plugins/terminal/shortcutmap.h
index e3de7e01bdf..956c3b5c9e7 100644
--- a/src/plugins/terminal/shortcutmap.h
+++ b/src/plugins/terminal/shortcutmap.h
@@ -7,8 +7,10 @@
 #include <QKeySequence>
 #include <QObject>
 
+QT_BEGIN_NAMESPACE
 class QKeyEvent;
 class QObject;
+QT_END_NAMESPACE
 
 namespace Terminal::Internal {
 
diff --git a/src/shared/proparser/qmakeevaluator.h b/src/shared/proparser/qmakeevaluator.h
index 8b4a9e79aaf..da681b3bbe6 100644
--- a/src/shared/proparser/qmakeevaluator.h
+++ b/src/shared/proparser/qmakeevaluator.h
@@ -45,12 +45,11 @@ public:
     int exitCode = 0;
 };
 
+QT_BEGIN_NAMESPACE
+
 QMAKE_EXPORT std::function<void(ProcessData *data)> &theProcessRunner();
 QMAKE_EXPORT QString removeHostAndScheme(const QString &remotePath);
 
-
-QT_BEGIN_NAMESPACE
-
 class QMakeGlobals;
 
 class QMAKE_EXPORT QMakeHandler : public QMakeParserHandler
diff --git a/tests/auto/utils/filepath/tst_filepath.cpp b/tests/auto/utils/filepath/tst_filepath.cpp
index 3699ec6b2e8..f9e10d5e207 100644
--- a/tests/auto/utils/filepath/tst_filepath.cpp
+++ b/tests/auto/utils/filepath/tst_filepath.cpp
@@ -9,15 +9,17 @@
 #include <utils/hostosinfo.h>
 #include <utils/link.h>
 
-using namespace Utils;
-
+QT_BEGIN_NAMESPACE
 namespace QTest {
 template<>
-char *toString(const FilePath &filePath)
+char *toString(const Utils::FilePath &filePath)
 {
     return qstrdup(filePath.toString().toLocal8Bit().constData());
 }
 } // namespace QTest
+QT_END_NAMESPACE
+
+namespace Utils {
 
 class tst_filepath : public QObject
 {
@@ -737,7 +739,12 @@ public:
     ExpectedPass expectedPass = PassEverywhere;
 };
 
-Q_DECLARE_METATYPE(FromStringData);
+} // Utils
+
+
+Q_DECLARE_METATYPE(Utils::FromStringData);
+
+namespace Utils {
 
 void tst_filepath::fromString_data()
 {
@@ -1683,6 +1690,8 @@ void tst_filepath::sort_data()
         << QStringList{"b://b//b", "a://b//b", "a://a//b", "a://b//a", "a://a//a"};
 }
 
-QTEST_GUILESS_MAIN(tst_filepath)
+} // Utils
+
+QTEST_GUILESS_MAIN(Utils::tst_filepath)
 
 #include "tst_filepath.moc"
diff --git a/tests/auto/utils/fileutils/tst_fileutils.cpp b/tests/auto/utils/fileutils/tst_fileutils.cpp
index 198abf3398b..8208e634120 100644
--- a/tests/auto/utils/fileutils/tst_fileutils.cpp
+++ b/tests/auto/utils/fileutils/tst_fileutils.cpp
@@ -7,15 +7,33 @@
 #include <utils/hostosinfo.h>
 
 //TESTED_COMPONENT=src/libs/utils
-using namespace Utils;
 
+QT_BEGIN_NAMESPACE
 namespace QTest {
+
 template<>
-char *toString(const FilePath &filePath)
+char *toString(const Utils::FilePath &filePath)
 {
     return qstrdup(filePath.toString().toLocal8Bit().constData());
 }
+
+template<>
+char *toString(const Utils::FilePathInfo &filePathInfo)
+{
+    QByteArray ba = "FilePathInfo(";
+    ba += QByteArray::number(filePathInfo.fileSize);
+    ba += ", ";
+    ba += QByteArray::number(filePathInfo.fileFlags, 16);
+    ba += ", ";
+    ba += filePathInfo.lastModified.toString().toUtf8();
+    ba += ")";
+    return qstrdup(ba.constData());
+}
+
 } // namespace QTest
+QT_END_NAMESPACE
+
+using namespace Utils;
 
 class tst_fileutils : public QObject
 {
@@ -183,23 +201,6 @@ void tst_fileutils::filePathInfoFromTriple()
     QCOMPARE(result, expected);
 }
 
-QT_BEGIN_NAMESPACE
-namespace QTest {
-template<>
-char *toString(const FilePathInfo &filePathInfo)
-{
-    QByteArray ba = "FilePathInfo(";
-    ba += QByteArray::number(filePathInfo.fileSize);
-    ba += ", ";
-    ba += QByteArray::number(filePathInfo.fileFlags, 16);
-    ba += ", ";
-    ba += filePathInfo.lastModified.toString().toUtf8();
-    ba += ")";
-    return qstrdup(ba.constData());
-}
-
-} // namespace QTest
-
 QTEST_GUILESS_MAIN(tst_fileutils)
 
 #include "tst_fileutils.moc"
diff --git a/tests/auto/utils/unixdevicefileaccess/tst_unixdevicefileaccess.cpp b/tests/auto/utils/unixdevicefileaccess/tst_unixdevicefileaccess.cpp
index b5aef12d06c..3e62be9147d 100644
--- a/tests/auto/utils/unixdevicefileaccess/tst_unixdevicefileaccess.cpp
+++ b/tests/auto/utils/unixdevicefileaccess/tst_unixdevicefileaccess.cpp
@@ -12,15 +12,18 @@
 #include <utils/link.h>
 
 //TESTED_COMPONENT=src/libs/utils
-using namespace Utils;
 
+QT_BEGIN_NAMESPACE
 namespace QTest {
 template<>
-char *toString(const FilePath &filePath)
+char *toString(const Utils::FilePath &filePath)
 {
     return qstrdup(filePath.toString().toLocal8Bit().constData());
 }
 } // namespace QTest
+QT_END_NAMESPACE
+
+using namespace Utils;
 
 class TestDFA : public UnixDeviceFileAccess
 {