diff --git a/configure.in b/configure.in
index 1ac6d2c82..e55b02a58 100644
--- a/configure.in
+++ b/configure.in
@@ -43,15 +43,16 @@ AC_CONFIG_SUBDIRS(guile-readline)
 #
 #--------------------------------------------------------------------
 
+GUILE_ERROR_ON_WARNING="yes"
+
 AC_ARG_ENABLE(error-on-warning,
   [  --enable-error-on-warning    treat compile warnings as errors],
   [case "${enableval}" in
-     yes | y) CFLAGS="${CFLAGS} -Werror"; enable_compile_warnings=no ;;
-     no | n)  ;;
+     yes | y) GUILE_ERROR_ON_WARNING="yes" ;;
+     no | n)  GUILE_ERROR_ON_WARNING="no" ;;
      *) AC_MSG_ERROR(bad value ${enableval} for --enable-error-on-warning) ;;
    esac])
 
-
 AC_ARG_ENABLE(debug-freelist,
   [  --enable-debug-freelist include garbage collector freelist debugging code],
   if test "$enable_debug_freelist" = y || test "$enable_debug_freelist" = yes; then
@@ -150,13 +151,10 @@ AC_CYGWIN
 AC_MINGW32
 AC_LIBTOOL_WIN32_DLL
 
-AC_LIBLTDL_CONVENIENCE
-AC_CONFIG_SUBDIRS(libltdl)
-
 AC_PROG_INSTALL
 AC_PROG_CC
 AC_PROG_CPP
-AC_LIBTOOL_DLOPEN
+AC_PROG_AWK
 
 AC_AIX
 AC_ISC_POSIX
@@ -164,9 +162,9 @@ AC_MINIX
 
 AM_PROG_CC_STDC
 
-## Needed for building DLLs on Cygwin, before AM_PROG_LIBTOOL
-AC_LIBTOOL_WIN32_DLL
+AC_LIBTOOL_DLOPEN
 AM_PROG_LIBTOOL
+AC_LIB_LTDL
 
 AC_CHECK_PROG(have_makeinfo, makeinfo, yes, no)
 AM_CONDITIONAL(HAVE_MAKEINFO, test "$have_makeinfo" = yes)
@@ -264,7 +262,13 @@ AC_HEADER_STDC
 AC_HEADER_DIRENT
 AC_HEADER_TIME
 AC_HEADER_SYS_WAIT
-AC_CHECK_HEADERS(io.h libc.h limits.h malloc.h memory.h string.h regex.h rxposix.h rx/rxposix.h sys/ioctl.h sys/select.h sys/time.h sys/timeb.h sys/times.h sys/stdtypes.h sys/types.h sys/utime.h time.h unistd.h utime.h pwd.h grp.h sys/utsname.h direct.h)
+
+AC_CHECK_HEADERS([io.h libc.h limits.h malloc.h memory.h string.h \
+regex.h rxposix.h rx/rxposix.h sys/dir.h sys/ioctl.h sys/select.h \
+sys/time.h sys/timeb.h sys/times.h sys/stdtypes.h sys/types.h \
+sys/utime.h time.h unistd.h utime.h pwd.h grp.h sys/utsname.h \
+direct.h])
+
 GUILE_HEADER_LIBC_WITH_UNISTD
 
 AC_TYPE_GETGROUPS
@@ -306,11 +310,15 @@ if test "$MINGW32" = "yes" ; then
 fi
 AC_SUBST(EXTRA_DEFS)
 
-AC_SUBST(INCLTDL)
-AC_SUBST(LIBLTDL)
+# FIXME: check to see if we still need these.
+#AC_SUBST(INCLTDL)
+#AC_SUBST(LIBLTDL)
+
 AC_SUBST(DLPREOPEN)
 
-AC_CHECK_FUNCS(ctermid ftime fchown getcwd geteuid gettimeofday lstat mkdir mknod nice readlink rename rmdir select setegid seteuid setlocale setpgid setsid sigaction siginterrupt strftime strptime symlink sync tcgetpgrp tcsetpgrp times uname waitpid strdup system usleep atexit on_exit chown link fcntl ttyname getpwent getgrent kill getppid getpgrp fork setitimer getitimer)
+AC_CHECK_HEADERS([assert.h])
+
+AC_CHECK_FUNCS([ctermid ftime fchown getcwd geteuid gettimeofday lstat mkdir mknod nice readlink rename rmdir select setegid seteuid setlocale setpgid setsid sigaction siginterrupt strftime strptime symlink sync tcgetpgrp tcsetpgrp times uname waitpid strdup system usleep atexit on_exit chown link fcntl ttyname getpwent getgrent kill getppid getpgrp fork setitimer getitimer strchr strcmp index bcopy memcpy rindex])
 
 AC_CHECK_HEADERS(crypt.h sys/resource.h sys/file.h)
 AC_CHECK_FUNCS(chroot flock getlogin cuserid getpriority setpriority getpass sethostname gethostname)
@@ -739,6 +747,15 @@ if test "$cross_compiling" = "yes"; then
 fi
 AC_SUBST(GUILE_FOR_BUILD)
   			
+# Do this here so we don't screw up any of the tests above that might
+# not be "warning free"
+
+if test "${GUILE_ERROR_ON_WARNING}" = yes
+then
+  CFLAGS="${CFLAGS} -Werror"
+  enable_compile_warnings=no
+fi
+
 ## If we're using GCC, ask for aggressive warnings.
 case "$GCC" in
   yes )
@@ -750,8 +767,6 @@ case "$GCC" in
     CFLAGS="$CFLAGS -Wall -Wmissing-prototypes" ;;
 esac
 
-AC_PROG_AWK
-
 ## NOTE the code below sets LIBOBJS directly and so is now forbidden
 ## -- I'm disabling it for now in the hopes that the newer autoconf
 ## will DTRT -- if not, we need to fix up the sed command to match the
@@ -824,6 +839,8 @@ AC_CONFIG_FILES([
   libguile/guile-func-name-check
   libguile/guile-snarf-docs
   libguile/version.h
+  libguile-ltdl/Makefile
+  libguile-ltdl/upstream/Makefile
   ice-9/Makefile
   lang/Makefile
   lang/elisp/Makefile