--- libsrc/stlgeom/Makefile.am.orig	2016-04-21 10:58:05 UTC
+++ libsrc/stlgeom/Makefile.am
@@ -1,7 +1,7 @@
 noinst_HEADERS = meshstlsurface.hpp stlgeom.hpp stlline.hpp \
 stltool.hpp stltopology.hpp vsstl.hpp
 
-AM_CPPFLAGS = -I$(top_srcdir)/libsrc/include $(TCL_INCLUDES)
+AM_CPPFLAGS = -I$(top_srcdir)/libsrc/include $(TCL_INCLUDES) $(TK_INCLUDES)
 METASOURCES = AUTO
 
 lib_LTLIBRARIES = libstl.la