diff --git a/src/corelib/io/qdebug.cpp b/src/corelib/io/qdebug.cpp
index 56deeb7cf75..240cc2ea959 100644
--- a/src/corelib/io/qdebug.cpp
+++ b/src/corelib/io/qdebug.cpp
@@ -347,12 +347,7 @@ void QDebug::putByteArray(const char *begin, size_t length, Latin1Content conten
     }
 }
 
-/*!
-    \since 6.6
-    \internal
-    Helper to the std::chrono::duration debug streaming output.
- */
-QByteArray QDebug::timeUnit(qint64 num, qint64 den)
+static QByteArray timeUnit(qint64 num, qint64 den)
 {
     using namespace std::chrono;
     using namespace q20::chrono;
@@ -431,6 +426,16 @@ QByteArray QDebug::timeUnit(qint64 num, qint64 den)
     return QByteArray(buf, len + strlen(unit));
 }
 
+/*!
+    \since 6.6
+    \internal
+    Helper to the std::chrono::duration debug streaming output.
+ */
+void QDebug::putTimeUnit(qint64 num, qint64 den)
+{
+    stream->ts << timeUnit(num, den); // ### optimize
+}
+
 /*!
     \fn QDebug::swap(QDebug &other)
     \since 5.0
diff --git a/src/corelib/io/qdebug.h b/src/corelib/io/qdebug.h
index 7390a9c8bce..8469a4a8206 100644
--- a/src/corelib/io/qdebug.h
+++ b/src/corelib/io/qdebug.h
@@ -68,7 +68,7 @@ class QT6_ONLY(Q_CORE_EXPORT) QDebug : public QIODeviceBase
     QT7_ONLY(Q_CORE_EXPORT) void putUcs4(uint ucs4);
     QT7_ONLY(Q_CORE_EXPORT) void putString(const QChar *begin, size_t length);
     QT7_ONLY(Q_CORE_EXPORT) void putByteArray(const char *begin, size_t length, Latin1Content content);
-    QT7_ONLY(Q_CORE_EXPORT) static QByteArray timeUnit(qint64 num, qint64 den);
+    QT7_ONLY(Q_CORE_EXPORT) void putTimeUnit(qint64 num, qint64 den);
 public:
     explicit QDebug(QIODevice *device) : stream(new Stream(device)) {}
     explicit QDebug(QString *string) : stream(new Stream(string)) {}
@@ -194,7 +194,8 @@ public:
     template <typename Rep, typename Period>
     QDebug &operator<<(std::chrono::duration<Rep, Period> duration)
     {
-        stream->ts << duration.count() << timeUnit(Period::num, Period::den);
+        stream->ts << duration.count();
+        putTimeUnit(Period::num, Period::den);
         return maybeSpace();
     }