diff --git a/README.md b/README.md
index b200585..064b1c2 100644
--- a/README.md
+++ b/README.md
@@ -73,6 +73,7 @@ Dependencies
 * `libsystemd` - systemd library containing sd-bus implementation. This library is part of systemd. Systemd at least v236 is needed. (In case you have a non-systemd environment, don't worry, see [Solving libsystemd dependency](docs/using-sdbus-c++.md#solving-libsystemd-dependency) for more information.)
 * `googletest` - google unit testing framework, only necessary when building tests, will be downloaded and built automatically.
 * `pkgconfig` - required for sdbus-c++ to be able to find some dependency packages.
+* `expat` - necessary when building xml2cpp code generator (`BUILD_CODE_GEN` option is ON).
 
 Licensing
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