diff --git a/config.mk b/config.mk
index 514c236..ebb4b87 100644
--- a/config.mk
+++ b/config.mk
@@ -7,23 +7,23 @@ VERSION = 1.5
 PREFIX = /usr/local
 MANPREFIX = ${PREFIX}/share/man
 
-X11INC = /usr/X11R6/include
-X11LIB = /usr/X11R6/lib
+X11INC = /usr/include/X11
+X11LIB = /usr/lib/X11
 
 # includes and libs
 INCS = -I. -I/usr/include -I${X11INC}
 LIBS = -L/usr/lib -lc -lcrypt -L${X11LIB} -lX11 -lXext -lXrandr
 
 # flags
-CPPFLAGS = -DVERSION=\"${VERSION}\" -D_DEFAULT_SOURCE -DHAVE_SHADOW_H
-CFLAGS = -std=c99 -pedantic -Wall -Os ${INCS} ${CPPFLAGS}
-LDFLAGS = -s ${LIBS}
+CPPFLAGS += -DVERSION=\"${VERSION}\" -D_DEFAULT_SOURCE -DHAVE_SHADOW_H
+CFLAGS += -std=c99 -pedantic -Wall -Os ${INCS} ${CPPFLAGS}
+LDFLAGS += -s ${LIBS}
 COMPATSRC = explicit_bzero.c
 
 # On OpenBSD and Darwin remove -lcrypt from LIBS
 #LIBS = -L/usr/lib -lc -L${X11LIB} -lX11 -lXext -lXrandr
 # On *BSD remove -DHAVE_SHADOW_H from CPPFLAGS
 # On NetBSD add -D_NETBSD_SOURCE to CPPFLAGS
-#CPPFLAGS = -DVERSION=\"${VERSION}\" -D_BSD_SOURCE -D_NETBSD_SOURCE
+#CPPFLAGS += -DVERSION=\"${VERSION}\" -D_BSD_SOURCE -D_NETBSD_SOURCE
 # On OpenBSD set COMPATSRC to empty
 #COMPATSRC =