diff --git a/Doc/library/ctypes.rst b/Doc/library/ctypes.rst
index b968613..f4c6e2d 100644
--- a/Doc/library/ctypes.rst
+++ b/Doc/library/ctypes.rst
@@ -2159,6 +2159,7 @@
    optional float initializer.  On platforms where ``sizeof(long
    double) == sizeof(double)`` it is an alias to :class:`c_double`.
 
+   .. versionadded:: 2.6
 
 .. class:: c_float