diff --git a/doc/build-unix.md b/doc/build-unix.md
index 6cf88edff..b53d69342 100644
--- a/doc/build-unix.md
+++ b/doc/build-unix.md
@@ -93,7 +93,7 @@ are installed. Qt 4 is currently necessary to build the GUI.
 
 To build with Qt 4 you need the following:
 
-    apt-get install libqt4-dev libprotobuf-dev
+    apt-get install libqt4-dev libprotobuf-dev protobuf-compiler
 
 libqrencode (optional) can be installed with: