diff --git a/INSTALL.md b/INSTALL.md
index f3c4f54..2404ebe 100644
--- a/INSTALL.md
+++ b/INSTALL.md
@@ -55,7 +55,7 @@ Generate a new SSH key with a blank password:
     $ ssh-keygen -t rsa -f config/ssh-host-key
 
 Install PostgreSQL. You'll need the server and the client library development
-files.
+files. Note that PostgreSQL needs to be at least version 9.5.
 
     $ sudo apt install postgresql libpq-dev