diff --git a/Doc/c-api/float.rst b/Doc/c-api/float.rst
index 1085c32a537071..501a32c5bac95b 100644
--- a/Doc/c-api/float.rst
+++ b/Doc/c-api/float.rst
@@ -78,6 +78,15 @@ Floating-Point Objects
    Return the minimum normalized positive float *DBL_MIN* as C :c:expr:`double`.
 
 
+.. c:macro:: Py_INFINITY
+
+   This is equivalent to the :c:macro:`!INFINITY` macro from the C11 standard
+   ``<math.h>`` header.
+
+   .. deprecated:: 3.15
+      The macro is soft deprecated.
+
+
 .. c:macro:: Py_RETURN_NAN
 
    Return :data:`math.nan` from a function.