Index: config.h.in
==================================================================
--- config.h.in
+++ config.h.in
@@ -1,9 +1,12 @@
 /* config.h.in.  Generated from configure.in by autoheader.  */
 
 /* Define if building universal (internal helper macro) */
 #undef AC_APPLE_UNIVERSAL_BUILD
+
+/* Should always be 1 */
+#undef BUILD_TclOO
 
 /* Do we have the intptr_t type? */
 #undef HAVE_INTPTR_T
 
 /* Define to 1 if you have the <inttypes.h> header file. */

Index: configure
==================================================================
--- configure
+++ configure
@@ -7843,10 +7843,14 @@
 CLEANFILES="${CLEANFILES} pkgIndex.tcl"
 
 
 $as_echo "#define USE_TCL_STUBS 1" >>confdefs.h
 
+
+
+$as_echo "#define BUILD_TclOO 1" >>confdefs.h
+
 
 
     { $as_echo "$as_me:${as_lineno-$LINENO}: checking for tclsh" >&5
 $as_echo_n "checking for tclsh... " >&6; }
     if test -f "${TCL_BIN_DIR}/Makefile" ; then

Index: configure.in
==================================================================
--- configure.in
+++ configure.in
@@ -54,10 +54,14 @@
 dnl TEAX_VC_MANIFEST
 
 TEAX_LAPPEND(CLEANFILES, pkgIndex.tcl)
 AC_SUBST(CLEANFILES)
 AC_DEFINE(USE_TCL_STUBS,[1],[Should always be 1])
+
+dnl# This is necessary to ensure that invocations of autoheader
+dnl# generate a config.in.h that includes the BUILD_TclOO directive.
+AC_DEFINE([BUILD_TclOO], [1], [Should always be 1])
 
 TEA_PROG_TCLSH
 CONFIGURE_OUTPUTS="Makefile tclooConfig.sh config.cache config.log config.status"
 AC_SUBST(CONFIGURE_OUTPUTS)