diff --git a/src/corelib/tools/qarraydatapointer.h b/src/corelib/tools/qarraydatapointer.h
index 55540d10a43..75ca2af3a0d 100644
--- a/src/corelib/tools/qarraydatapointer.h
+++ b/src/corelib/tools/qarraydatapointer.h
@@ -450,7 +450,7 @@ public:
     qsizetype constAllocatedCapacity() const noexcept { return d ? d->constAllocatedCapacity() : 0; }
     void ref() noexcept { if (d) d->ref(); }
     bool deref() noexcept { return !d || d->deref(); }
-    bool isMutable() const noexcept { return d; }
+    bool isMutable() const noexcept { return d; } // Returns false if this object is fromRawData()
     bool isShared() const noexcept { return !d || d->isShared(); }
     bool isSharedWith(const QArrayDataPointer &other) const noexcept { return d && d == other.d; }
     bool needsDetach() const noexcept { return !d || d->needsDetach(); }