Index: tcl.m4
==================================================================
--- tcl.m4
+++ tcl.m4
@@ -51,10 +51,14 @@
 	no_tcl=true
 	AC_ARG_WITH(tcl,
 	    AS_HELP_STRING([--with-tcl],
 		[directory containing tcl configuration (tclConfig.sh)]),
 	    [with_tclconfig="${withval}"])
+	AC_ARG_WITH(tcl8,
+	    AS_HELP_STRING([--with-tcl8],
+		[Compile for Tcl8 in Tcl9 environment]),
+	    [with_tcl8="${withval}"])
 	AC_MSG_CHECKING([for Tcl configuration])
 	AC_CACHE_VAL(ac_cv_c_tclconfig,[
 
 	    # First check to see if --with-tcl was specified.
 	    if test x"${with_tclconfig}" != x ; then
@@ -3172,14 +3176,15 @@
     # substituted. (@@@ Might not be necessary anymore)
     #--------------------------------------------------------------------
 
     PACKAGE_LIB_PREFIX8="${PACKAGE_LIB_PREFIX}"
     PACKAGE_LIB_PREFIX9="${PACKAGE_LIB_PREFIX}tcl9"
-    if test "${TCL_MAJOR_VERSION}" -gt 8 ; then
+    if test "${TCL_MAJOR_VERSION}" -gt 8 -a x"${with_tcl8}" == x; then
 	PACKAGE_LIB_PREFIX="${PACKAGE_LIB_PREFIX9}"
     else
 	PACKAGE_LIB_PREFIX="${PACKAGE_LIB_PREFIX8}"
+	AC_DEFINE(TCL_MAJOR_VERSION, 8, [Compile for Tcl8?])
     fi
     if test "${TEA_PLATFORM}" = "windows" ; then
 	if test "${SHARED_BUILD}" = "1" ; then
 	    # We force the unresolved linking of symbols that are really in
 	    # the private libraries of Tcl and Tk.