diff --git a/source/_components/tradfri.markdown b/source/_components/tradfri.markdown
index e7f4e9e09f4..0d6319cf2ee 100644
--- a/source/_components/tradfri.markdown
+++ b/source/_components/tradfri.markdown
@@ -20,6 +20,7 @@ For this to work, you need to install a modified lib-coap library:
 
 ```bash
 $ sudo apt-get install libtool
+$ sudo apt-get install autoconf
 
 $ git clone --depth 1 --recursive -b dtls https://github.com/home-assistant/libcoap.git
 $ cd libcoap