diff --git a/README.md b/README.md
index 4162e678..cbc79d37 100644
--- a/README.md
+++ b/README.md
@@ -24,6 +24,7 @@ Just install `xpra-html5` from there.
 
 To install from source:
 ```
+sudo apt install uglifyjs
 git clone https://github.com/Xpra-org/xpra-html5
 cd xpra-html5
 ./setup.py install