diff --git a/diff.c b/diff.c
index 2c904e0526..e51f6b3005 100644
--- a/diff.c
+++ b/diff.c
@@ -5060,6 +5060,9 @@ static void prep_parse_options(struct diff_options *options)
 			       N_("detect renames"),
 			       PARSE_OPT_NONEG | PARSE_OPT_OPTARG,
 			       diff_opt_find_renames),
+		OPT_SET_INT_F('D', "irreversible-delete", &options->irreversible_delete,
+			      N_("omit the preimage for deletes"),
+			      1, PARSE_OPT_NONEG),
 
 		OPT_GROUP(N_("Diff other options")),
 		{ OPTION_CALLBACK, 0, "output", options, N_("<file>"),
@@ -5094,10 +5097,7 @@ int diff_opt_parse(struct diff_options *options,
 		return ac;
 
 	/* renames options */
-	if (!strcmp(arg, "-D") || !strcmp(arg, "--irreversible-delete")) {
-		options->irreversible_delete = 1;
-	}
-	else if (starts_with(arg, "-C") ||
+	if (starts_with(arg, "-C") ||
 		 skip_to_optional_arg(arg, "--find-copies", NULL)) {
 		if (options->detect_rename == DIFF_DETECT_COPY)
 			options->flags.find_copies_harder = 1;