diff --git a/config.mk b/config.mk
index 3b00d7e..d801515 100644
--- a/config.mk
+++ b/config.mk
@@ -4,7 +4,7 @@ VERSION = 0.8.1
 # Customize below to fit your system
 
 # paths
-PREFIX = /usr/local
+PREFIX ?= /usr/local
 MANPREFIX = $(PREFIX)/share/man
 
 X11INC = /usr/X11R6/include