diff --git a/src/fmail.c b/src/fmail.c
index a5051b3..415ffad 100644
--- a/src/fmail.c
+++ b/src/fmail.c
@@ -559,7 +559,7 @@ main(int argc, char *argv[])
     ctx.footer = NULL;
     ctx.input = stdin;
 
-    while ( (c = getopt_long(argc, argv, "hvsa:ef:H:F:T:C:S:",
+    while ( (c = getopt_long(argc, argv, "hvsa:ef:H:F:T:C:S:UD",
                              options, NULL)) != -1 ) {
         switch ( c ) {
         case 'h':