diff.c |   26 +++++++++++++++++---------
 diff.h |    1 +
 2 files changed, 18 insertions(+), 9 deletions(-)

diff --git a/diff.c b/diff.c
index 9fa841010cc2..c93fdaaa541f 100644
--- a/diff.c
+++ b/diff.c
@@ -1447,7 +1447,7 @@ static void show_numstat(struct diffstat_t *data, struct diff_options *options)
 
 struct dirstat_file {
 	const char *name;
-	unsigned long changed;
+	long changed;
 };
 
 struct dirstat_dir {
@@ -1458,7 +1458,7 @@ struct dirstat_dir {
 static long gather_dirstat(struct diff_options *opt, struct dirstat_dir *dir,
 		unsigned long changed, const char *base, int baselen)
 {
-	unsigned long this_dir = 0;
+	long this_dir = 0;
 	unsigned int sources = 0;
 	const char *line_prefix = "";
 	struct strbuf *msg = NULL;
@@ -1499,12 +1499,14 @@ static long gather_dirstat(struct diff_options *opt, struct dirstat_dir *dir,
 	 *    under this directory (sources == 1).
 	 */
 	if (baselen && sources != 1) {
-		int permille = this_dir * 1000 / changed;
+		int permille = labs(this_dir) * 1000 / changed;
 		if (permille) {
-			int percent = permille / 10;
+			double percent = permille / 10.0;
 			if (percent >= dir->percent) {
-				fprintf(opt->file, "%s%4d.%01d%% %.*s\n", line_prefix,
-					percent, permille % 10, baselen, base);
+				if (this_dir < 0)
+					percent = -percent;
+				fprintf(opt->file, "%s%6.1f%% %.*s\n", line_prefix,
+					percent, baselen, base);
 				if (!dir->cumulative)
 					return 0;
 			}
@@ -1537,7 +1539,8 @@ static void show_dirstat(struct diff_options *options)
 	for (i = 0; i < q->nr; i++) {
 		struct diff_filepair *p = q->queue[i];
 		const char *name;
-		unsigned long copied, added, damage;
+		unsigned long copied, added, deleted;
+		long damage;
 
 		name = p->one->path ? p->one->path : p->two->path;
 
@@ -1567,7 +1570,11 @@ static void show_dirstat(struct diff_options *options)
 		 * damaged files, not damaged lines. This is done by
 		 * counting only a single damaged line per file.
 		 */
-		damage = (p->one->size - copied) + added;
+		deleted = p->one->size - copied;
+		if (DIFF_OPT_TST(options, DIFFSTAT_NEGATIVE))
+			damage = added - deleted;
+		else
+			damage = added + deleted;
 		if (DIFF_OPT_TST(options, DIRSTAT_BY_FILE) && damage > 0)
 			damage = 1;
 
@@ -3139,7 +3146,8 @@ int diff_opt_parse(struct diff_options *options, const char **av, int ac)
 			   &options->dirstat_percent)) {
 		options->output_format |= DIFF_FORMAT_DIRSTAT;
 		DIFF_OPT_SET(options, DIRSTAT_BY_FILE);
-	}
+	} else if (!strcmp(arg, "--negative"))
+		DIFF_OPT_SET(options, DIFFSTAT_NEGATIVE);
 	else if (!strcmp(arg, "--check"))
 		options->output_format |= DIFF_FORMAT_CHECKDIFF;
 	else if (!strcmp(arg, "--summary"))
diff --git a/diff.h b/diff.h
index 007a0554d4b2..95d6e65247ae 100644
--- a/diff.h
+++ b/diff.h
@@ -78,6 +78,7 @@ typedef struct strbuf *(*diff_prefix_fn_t)(struct diff_options *opt, void *data)
 #define DIFF_OPT_IGNORE_UNTRACKED_IN_SUBMODULES (1 << 25)
 #define DIFF_OPT_IGNORE_DIRTY_SUBMODULES (1 << 26)
 #define DIFF_OPT_OVERRIDE_SUBMODULE_CONFIG (1 << 27)
+#define DIFF_OPT_DIFFSTAT_NEGATIVE   (1 << 28)
 
 #define DIFF_OPT_TST(opts, flag)    ((opts)->flags & DIFF_OPT_##flag)
 #define DIFF_OPT_SET(opts, flag)    ((opts)->flags |= DIFF_OPT_##flag)