diff --git a/README.md b/README.md
index d225050..f95ebe5 100644
--- a/README.md
+++ b/README.md
@@ -27,6 +27,7 @@ require "db"
 require "sqlite3"
 
 DB.open "sqlite3:./file.db" do |db|
+  # When using the pg driver, use $1, $2, etc. instead of ?
   db.exec "create table contacts (name string, age integer)"
   db.exec "insert into contacts values (?, ?)", "John Doe", 30