diff --git a/README b/README
index c846c7a2a..4c34e693f 100644
--- a/README
+++ b/README
@@ -8,6 +8,7 @@ Linphone for iPhone depends on liblinphone sdk. To build this sdk, you must inst
 -intltool
 -wget
 -pkgconfig
+-cmake (for ZRTP support)
 
 Link macport libtoolize to glibtoolize (sudo ln -s /opt/local/bin/glibtoolize /opt/local/bin/libtoolize)