As X11 includes live in /usr/include on linux the previous
path was wrong anyway so switch to a path which should work
on other systems (does not break linux).
-XINCLUDE = /usr/include/X11
+XINCLUDE = /usr/X11R6/include
 TCLHOME = ../tcl
 TKHOME = ../tk
 TCLXHOME = ../tclx
 
 RANLIB_CMD=ranlib
 MCS_CMD=true
 TCL_TK_LIBS= -L/usr/X11/lib -lX11 -lm -lXpm
-XINCLUDE=/usr/include/X11
+XINCLUDE=/usr/X11R6/include
 
 TCL_MAN_SEPARATOR=
 
 
 TCL_DIR                = ../tcl
 TCLX_DIR       = ../tclx/src
-XINCLUDE       = /usr/include/X11
+XINCLUDE       = /usr/X11R6/include
 XLIB           = -L/usr/X11R6/lib -lX11 -lXpm
 
 LIBS = libtk.a $(TCL_DIR)/libtcl.a