diff --git a/config.mk b/config.mk
index 67931f6..a9090fe 100755
--- a/config.mk
+++ b/config.mk
@@ -7,8 +7,8 @@ VERSION = 0.9.2
 PREFIX = /usr/local
 MANPREFIX = $(PREFIX)/share/man
 
-X11INC = /usr/include
-X11LIB = /usr/lib
+X11INC = ${PREFIX}/include
+X11LIB = ${PREFIX}/lib
 
 PKG_CONFIG = pkg-config