diff --git a/Doc/c-api/float.rst b/Doc/c-api/float.rst
index 4f6ac0d8175c6b..2cbbf2a7c751cf 100644
--- a/Doc/c-api/float.rst
+++ b/Doc/c-api/float.rst
@@ -162,3 +162,12 @@ represents a NaN or infinity.
 .. c:function:: double PyFloat_Unpack8(const unsigned char *p, int le)
 
    Unpack the IEEE 754 binary64 double precision format as a C double.
+
+Constants
+^^^^^^^^^
+
+.. c:macro:: PY_BIG_ENDIAN
+
+   A constant which can be used by pack and unpack functions to use the native
+   endian: it is equal to ``1`` on big endian processor, or ``0`` on little
+   endian processor.
diff --git a/Doc/tools/.nitignore b/Doc/tools/.nitignore
index 8b0fc13832d51a..cf606916e48405 100644
--- a/Doc/tools/.nitignore
+++ b/Doc/tools/.nitignore
@@ -5,7 +5,6 @@
 Doc/c-api/descriptor.rst
 Doc/c-api/exceptions.rst
 Doc/c-api/file.rst
-Doc/c-api/float.rst
 Doc/c-api/gcsupport.rst
 Doc/c-api/init.rst
 Doc/c-api/init_config.rst