diff --git a/src/corelib/io/qiodevice.cpp b/src/corelib/io/qiodevice.cpp
index 5dd5f8031e..86e21f0a66 100644
--- a/src/corelib/io/qiodevice.cpp
+++ b/src/corelib/io/qiodevice.cpp
@@ -333,7 +333,7 @@ QIODevicePrivate::~QIODevicePrivate()
                      allowed. This flag currently only affects QFile. Other
                      classes might use this flag in the future, but until then
                      using this flag with any classes other than QFile may
-                     result in undefined behavior.
+                     result in undefined behavior. (since Qt 5.11)
     \value ExistingOnly Fail if the file to be opened does not exist. This flag
                      must be specified alongside ReadOnly, WriteOnly, or
                      ReadWrite. Note that using this flag with ReadOnly alone
@@ -341,7 +341,7 @@ QIODevicePrivate::~QIODevicePrivate()
                      not exist. This flag currently only affects QFile. Other
                      classes might use this flag in the future, but until then
                      using this flag with any classes other than QFile may
-                     result in undefined behavior.
+                     result in undefined behavior. (since Qt 5.11)
 
     Certain flags, such as \c Unbuffered and \c Truncate, are
     meaningless when used with some subclasses. Some of these