diff --git a/docs/source/c_api.rst b/docs/source/c_api.rst
index b94d0cd..1493a75 100644
--- a/docs/source/c_api.rst
+++ b/docs/source/c_api.rst
@@ -18,6 +18,8 @@ Macros
 
 .. doxygendefine:: DLPACK_FLAG_BITMASK_IS_COPIED
 
+.. doxygendefine:: DLPACK_FLAG_BITMASK_IS_SUBBYTE_TYPE_PADDED
+
 Enumerations
 ~~~~~~~~~~~~