diff --git a/INSTALL b/INSTALL
index 6c3bf31b6..d3b3f1a22 100644
--- a/INSTALL
+++ b/INSTALL
@@ -54,7 +54,7 @@ NOTE:	You should install all Ruby libraries with gem. Do not try
 
 XMPP4R				- [gem install xmpp4r]
 RMagick				- [gem install rmagick --no-ri --no-rdoc]
-postgres (>=0.7.9.2008.01.28)	- [gem install postgres]
+postgres (=0.7.9.2008.01.28)	- [gem install postgres -v '0.7.9.2008.01.28']
 Momomoto (>= 0.2.1)		- [gem install momomoto]
 shared-mime-info		- [gem install shared-mime-info]
 iCalendar			- [gem install icalendar]