diff --git a/INSTALL.md b/INSTALL.md
index 68c3808acd..75be6339dd 100644
--- a/INSTALL.md
+++ b/INSTALL.md
@@ -1,8 +1,8 @@
 ## Required packages
 
-Please install these packages before moving to next step. Below is a reference list for Debian-based distributions.
+Please install these packages before moving to next step. Below is a reference list for Debian-based distributions. Reference build system is Ubuntu 18.04/20.04 amd64.
 
-    subversion git-core gcc g++ make gawk bison flex bzip2 netpbm autoconf    automake libx11-dev libxext-dev libc6-dev liblzo2-dev libxxf86vm-dev libpng-dev gcc-multilib libsdl1.2-dev byacc python-mako libxcursor-dev
+    subversion git-core gcc g++ make gawk bison flex bzip2 netpbm autoconf automake libx11-dev libxext-dev libc6-dev liblzo2-dev libxxf86vm-dev libpng-dev gcc-multilib libsdl1.2-dev byacc python-mako libxcursor-dev cmake
 
 ## Clone & build