diff --git a/src/corelib/io/qbuffer.cpp b/src/corelib/io/qbuffer.cpp
index 0dcc02459d..ba84428275 100644
--- a/src/corelib/io/qbuffer.cpp
+++ b/src/corelib/io/qbuffer.cpp
@@ -267,8 +267,6 @@ void QBuffer::setData(const QByteArray &data)
 }
 
 /*!
-    \fn void QBuffer::setData(const char *data, qsizetype size)
-
     \overload
 
     Sets the contents of the internal buffer to be the first \a size
@@ -277,6 +275,16 @@ void QBuffer::setData(const QByteArray &data)
     \note In Qt versions prior to 6.5, this function took the length as
     an \c{int} parameter, potentially truncating sizes.
 */
+void QBuffer::setData(const char *data, qsizetype size)
+{
+    Q_D(QBuffer);
+    if (isOpen()) {
+        qWarning("QBuffer::setData: Buffer is open");
+        return;
+    }
+    d->buf->replace(qsizetype(0), d->buf->size(), // ### QByteArray lacks assign(ptr, n)
+                    data, size);
+}
 
 /*!
    \reimp
diff --git a/src/corelib/io/qbuffer.h b/src/corelib/io/qbuffer.h
index a7c6bde562..4cbbfe7c52 100644
--- a/src/corelib/io/qbuffer.h
+++ b/src/corelib/io/qbuffer.h
@@ -36,8 +36,7 @@ public:
 #if QT_CORE_REMOVED_SINCE(6, 5) && QT_POINTER_SIZE != 4
     void setData(const char *data, int len) { setData(data, qsizetype(len)); }
 #endif
-    void setData(const char *data, qsizetype len)
-    { setData(QByteArray(data, len)); }
+    void setData(const char *data, qsizetype len);
     const QByteArray &data() const;
 
     bool open(OpenMode openMode) override;