diff --git a/README.md b/README.md
index f2eecbc..11dda52 100644
--- a/README.md
+++ b/README.md
@@ -245,6 +245,7 @@ Available options:
 - [json](https://rubygems.org/gems/json)
 - [extlz4](https://rubygems.org/gems/extlz4)
 - [extlzma2](https://rubygems.org/gems/extlzma2)
+  - extlzma2 requires liblzma. You may need a `--with-liblzma-dir=` argument to install extlzma2.
 - [bin_utils](https://rubygems.org/gems/bin_utils)
 - [chunky_png](https://rubygems.org/gems/chunky_png)