diff --git a/readme.txt b/readme.txt
index 4b4c0229f4..db8fdd249a 100644
--- a/readme.txt
+++ b/readme.txt
@@ -661,6 +661,12 @@ The md5 implementation in src/3rdparty/md5 is licensed under the Zlib
 license. See the comments in the source files in src/3rdparty/md5 for
 the complete license text.
 
+The implementations of Posix getaddrinfo and getnameinfo for OS/2 in
+src/3rdparty/os2 are distributed partly under the GNU Lesser General Public
+License 2.1, and partly under the (3-clause) BSD license. The exact licensing
+terms can be found in src/3rdparty/os2/getaddrinfo.c resp.
+src/3rdparty/os2/getnameinfo.c.
+
 The exe2coff implementation in os/dos/exe2coff is available under the
 GPL, with a number of additional terms. See os/dos/exe2coff/copying and
 os/dos/exe2coff/copying.dj for the exact licensing terms.