diff --git a/autogen/config.in b/autogen/config.in
index 0f84754c11b..603101f51bf 100644
--- a/autogen/config.in
+++ b/autogen/config.in
@@ -126,6 +126,9 @@ along with GNU Emacs.  If not, see <http://www.gnu.org/licenses/>.  */
 /* Define to 1 for DGUX with <sys/dg_sys_info.h>. */
 #undef DGUX
 
+/* Character that separates directories in a file name. */
+#undef DIRECTORY_SEP
+
 /* Define if dispnew.c should include stdio_ext.h. */
 #undef DISPNEW_NEEDS_STDIO_EXT
 
diff --git a/autogen/configure b/autogen/configure
index 1215a147140..26da95952fc 100755
--- a/autogen/configure
+++ b/autogen/configure
@@ -14721,6 +14721,10 @@ $as_echo "#define USER_FULL_NAME pw->pw_gecos" >>confdefs.h
 
 
 
+$as_echo "#define DIRECTORY_SEP '/'" >>confdefs.h
+
+
+
 
 
 $as_echo "#define IS_DEVICE_SEP(_c_) 0" >>confdefs.h