diff --git a/Documentation/diff-options.txt b/Documentation/diff-options.txt
index b5d9763594..7b7b9e8ce9 100644
--- a/Documentation/diff-options.txt
+++ b/Documentation/diff-options.txt
@@ -10,8 +10,11 @@
 --patch-with-raw::
 	Synonym for "-p --raw".
 
---stat::
-	Generate a diffstat.
+--stat[=width[,name-width]]::
+	Generate a diffstat.  You can override the default
+	output width for 80-column terminal by "--stat=width".
+	The width of the filename part can be controlled by
+	giving another width to it separated by a comma.
 
 --summary::
 	Output a condensed summary of extended header information
diff --git a/diff.c b/diff.c
index 98c29bf0ff..c1379498c2 100644
--- a/diff.c
+++ b/diff.c
@@ -640,9 +640,12 @@ const char mime_boundary_leader[] = "------------";
 static int scale_linear(int it, int width, int max_change)
 {
 	/*
-	 * round(width * it / max_change);
+	 * make sure that at least one '-' is printed if there were deletions,
+	 * and likewise for '+'.
 	 */
-	return (it * width * 2 + max_change) / (max_change * 2);
+	if (max_change < 2)
+		return it;
+	return ((it - 1) * (width - 1) + max_change - 1) / (max_change - 1);
 }
 
 static void show_name(const char *prefix, const char *name, int len,
@@ -774,9 +777,9 @@ static void show_stats(struct diffstat_t* data, struct diff_options *options)
 		dels += del;
 
 		if (width <= max_change) {
-			total = scale_linear(total, width, max_change);
 			add = scale_linear(add, width, max_change);
-			del = total - add;
+			del = scale_linear(del, width, max_change);
+			total = add + del;
 		}
 		show_name(prefix, name, len, reset, set);
 		printf("%5d ", added + deleted);
@@ -1825,15 +1828,32 @@ int diff_opt_parse(struct diff_options *options, const char **av, int ac)
 	else if (!strcmp(arg, "--patch-with-raw")) {
 		options->output_format |= DIFF_FORMAT_PATCH | DIFF_FORMAT_RAW;
 	}
-	else if (!strcmp(arg, "--stat"))
-		options->output_format |= DIFF_FORMAT_DIFFSTAT;
-	else if (!strncmp(arg, "--stat-width=", 13)) {
-		options->stat_width = strtoul(arg + 13, NULL, 10);
-		options->output_format |= DIFF_FORMAT_DIFFSTAT;
-	}
-	else if (!strncmp(arg, "--stat-name-width=", 18)) {
-		options->stat_name_width = strtoul(arg + 18, NULL, 10);
+	else if (!strncmp(arg, "--stat", 6)) {
+		char *end;
+		int width = options->stat_width;
+		int name_width = options->stat_name_width;
+		arg += 6;
+		end = (char *)arg;
+
+		switch (*arg) {
+		case '-':
+			if (!strncmp(arg, "-width=", 7))
+				width = strtoul(arg + 7, &end, 10);
+			else if (!strncmp(arg, "-name-width=", 12))
+				name_width = strtoul(arg + 12, &end, 10);
+			break;
+		case '=':
+			width = strtoul(arg+1, &end, 10);
+			if (*end == ',')
+				name_width = strtoul(end+1, &end, 10);
+		}
+
+		/* Important! This checks all the error cases! */
+		if (*end)
+			return 0;
 		options->output_format |= DIFF_FORMAT_DIFFSTAT;
+		options->stat_name_width = name_width;
+		options->stat_width = width;
 	}
 	else if (!strcmp(arg, "--check"))
 		options->output_format |= DIFF_FORMAT_CHECKDIFF;