use the Include in srcdir
diff --git a/Makefile.pre.in b/Makefile.pre.in
index 99df1c1..300a668 100644
--- a/Makefile.pre.in
+++ b/Makefile.pre.in
@@ -73,7 +73,7 @@
# Both CPPFLAGS and LDFLAGS need to contain the shell's value for setup.py to
# be able to build extension modules using the directories specified in the
# environment variables
-PY_CPPFLAGS= -I. -IInclude $(CONFIGURE_CPPFLAGS) $(CPPFLAGS)
+PY_CPPFLAGS= -I. -I$(srcdir)/Include $(CONFIGURE_CPPFLAGS) $(CPPFLAGS)
PY_LDFLAGS= $(CONFIGURE_LDFLAGS) $(LDFLAGS)
NO_AS_NEEDED= @NO_AS_NEEDED@
LDLAST= @LDLAST@