diff --git a/src/corelib/text/qbytearrayview.h b/src/corelib/text/qbytearrayview.h
index 57d4711fdb..8d3ff0be67 100644
--- a/src/corelib/text/qbytearrayview.h
+++ b/src/corelib/text/qbytearrayview.h
@@ -40,14 +40,12 @@
 #define QBYTEARRAYVIEW_H
 
 #include <QtCore/qbytearrayalgorithms.h>
+#include <QtCore/qstringfwd.h>
 
 #include <string>
 
 QT_BEGIN_NAMESPACE
 
-class QByteArray;
-class QLatin1String;
-
 namespace QtPrivate {
 
 template <typename Byte>
diff --git a/src/corelib/text/qregularexpression.h b/src/corelib/text/qregularexpression.h
index 2d81d0c254..b5fee16057 100644
--- a/src/corelib/text/qregularexpression.h
+++ b/src/corelib/text/qregularexpression.h
@@ -54,8 +54,6 @@ QT_REQUIRE_CONFIG(regularexpression);
 
 QT_BEGIN_NAMESPACE
 
-class QLatin1String;
-
 class QRegularExpressionMatch;
 class QRegularExpressionMatchIterator;
 struct QRegularExpressionPrivate;
diff --git a/src/corelib/text/qutf8stringview.h b/src/corelib/text/qutf8stringview.h
index bec6f96953..76fd86b668 100644
--- a/src/corelib/text/qutf8stringview.h
+++ b/src/corelib/text/qutf8stringview.h
@@ -40,6 +40,7 @@
 #define QUTF8STRINGVIEW_H
 
 #include <QtCore/qstringalgorithms.h>
+#include <QtCore/qstringfwd.h>
 #include <QtCore/qarraydata.h> // for QContainerImplHelper
 #include <QtCore/qbytearrayview.h>
 
@@ -47,10 +48,6 @@
 
 QT_BEGIN_NAMESPACE
 
-template <bool> class QBasicUtf8StringView;
-class QByteArray;
-class QLatin1String;
-
 namespace QtPrivate {
 template <typename Char>
 using IsCompatibleChar8TypeHelper = std::disjunction<
diff --git a/src/corelib/tools/qhashfunctions.h b/src/corelib/tools/qhashfunctions.h
index a3e1600600..7aecd2c012 100644
--- a/src/corelib/tools/qhashfunctions.h
+++ b/src/corelib/tools/qhashfunctions.h
@@ -42,6 +42,7 @@
 #define QHASHFUNCTIONS_H
 
 #include <QtCore/qstring.h>
+#include <QtCore/qstringfwd.h>
 #include <QtCore/qpair.h>
 
 #include <numeric> // for std::accumulate
@@ -60,9 +61,6 @@
 QT_BEGIN_NAMESPACE
 
 class QBitArray;
-class QByteArray;
-class QString;
-class QLatin1String;
 
 #if QT_DEPRECATED_SINCE(6,6)
 QT_DEPRECATED_VERSION_X_6_6("Use QHashSeed instead")
diff --git a/src/testlib/qtestresult_p.h b/src/testlib/qtestresult_p.h
index 2034c006ad..d4a64e26ab 100644
--- a/src/testlib/qtestresult_p.h
+++ b/src/testlib/qtestresult_p.h
@@ -52,13 +52,11 @@
 //
 
 #include <QtTest/qttestglobal.h>
+#include <QtCore/qstringfwd.h>
 #include <QtCore/private/qglobal_p.h>
 
 QT_BEGIN_NAMESPACE
 
-class QLatin1String;
-class QStringView;
-
 class QTestResultPrivate;
 class QTestData;