diff --git a/doc/interprocess.qbk b/doc/interprocess.qbk
index 7b0fe68..a7d3243 100644
--- a/doc/interprocess.qbk
+++ b/doc/interprocess.qbk
@@ -6654,6 +6654,14 @@ those heavy headers.
 
 [endsect]
 
+[section:notes_cygwin Notes for Cygwin users]
+
+This library treats Cygwin as a Unix-like operating system and uses Unix-like system calls for the Cygwin platform instead
+of using the Windows API. You might need to define `_XOPEN_SOURCE=600` / `_POSIX_C_SOURCE=200112L` or higher so that the minimal Unix API
+is visible for the library.
+
+[endsect]
+
 [section:notes_linux Notes for Linux users]
 
 [section:notes_linux_shm_folder Shared memory emulation folder]