diff --git a/diff-cache.c b/diff-cache.c
index d573459ba4..963c628ed4 100644
--- a/diff-cache.c
+++ b/diff-cache.c
@@ -5,7 +5,7 @@ static int cached_only = 0;
 static int diff_output_format = DIFF_FORMAT_HUMAN;
 static int match_nonexisting = 0;
 static int detect_rename = 0;
-static int reverse_diff = 0;
+static int diff_setup_opt = 0;
 static int diff_score_opt = 0;
 static const char *pickaxe = NULL;
 
@@ -202,7 +202,7 @@ int main(int argc, const char **argv)
 			continue;
 		}
 		if (!strcmp(arg, "-R")) {
-			reverse_diff = 1;
+			diff_setup_opt |= DIFF_SETUP_REVERSE;
 			continue;
 		}
 		if (!strcmp(arg, "-S")) {
@@ -224,7 +224,7 @@ int main(int argc, const char **argv)
 		usage(diff_cache_usage);
 
 	/* The rest is for paths restriction. */
-	diff_setup(reverse_diff);
+	diff_setup(diff_setup_opt);
 
 	mark_merge_entries();
 
diff --git a/diff-files.c b/diff-files.c
index d7cfad79e7..c9c914be14 100644
--- a/diff-files.c
+++ b/diff-files.c
@@ -11,7 +11,7 @@ static const char *diff_files_usage =
 
 static int diff_output_format = DIFF_FORMAT_HUMAN;
 static int detect_rename = 0;
-static int reverse_diff = 0;
+static int diff_setup_opt = 0;
 static int diff_score_opt = 0;
 static const char *pickaxe = NULL;
 static int silent = 0;
@@ -51,7 +51,7 @@ int main(int argc, const char **argv)
 		else if (!strcmp(argv[1], "-z"))
 			diff_output_format = DIFF_FORMAT_MACHINE;
 		else if (!strcmp(argv[1], "-R"))
-			reverse_diff = 1;
+			diff_setup_opt |= DIFF_SETUP_REVERSE;
 		else if (!strcmp(argv[1], "-S"))
 			pickaxe = argv[1] + 2;
 		else if (!strncmp(argv[1], "-M", 2)) {
@@ -75,7 +75,7 @@ int main(int argc, const char **argv)
 		exit(1);
 	}
 
-	diff_setup(reverse_diff);
+	diff_setup(diff_setup_opt);
 
 	for (i = 0; i < entries; i++) {
 		struct stat st;
diff --git a/diff-tree.c b/diff-tree.c
index 80d02b4f5b..c41cdd0d2e 100644
--- a/diff-tree.c
+++ b/diff-tree.c
@@ -10,7 +10,7 @@ static int show_tree_entry_in_recursive = 0;
 static int read_stdin = 0;
 static int diff_output_format = DIFF_FORMAT_HUMAN;
 static int detect_rename = 0;
-static int reverse_diff = 0;
+static int diff_setup_opt = 0;
 static int diff_score_opt = 0;
 static const char *pickaxe = NULL;
 static const char *header = NULL;
@@ -255,7 +255,7 @@ static int diff_tree_sha1(const unsigned char *old, const unsigned char *new, co
 
 static void call_diff_setup(void)
 {
-	diff_setup(reverse_diff);
+	diff_setup(diff_setup_opt);
 }
 
 static int call_diff_flush(void)
@@ -497,7 +497,7 @@ int main(int argc, const char **argv)
 			continue;
 		}
 		if (!strcmp(arg, "-R")) {
-			reverse_diff = 1;
+			diff_setup_opt |= DIFF_SETUP_REVERSE;
 			continue;
 		}
 		if (!strcmp(arg, "-p")) {
diff --git a/diff.c b/diff.c
index f15eb08ef7..a11675551e 100644
--- a/diff.c
+++ b/diff.c
@@ -492,9 +492,10 @@ static void run_diff(const char *name,
 		run_external_diff(pgm, name, other, one, two, xfrm_msg);
 }
 
-void diff_setup(int reverse_diff_)
+void diff_setup(int flags)
 {
-	reverse_diff = reverse_diff_;
+	if (flags & DIFF_SETUP_REVERSE)
+		reverse_diff = 1;
 }
 
 struct diff_queue_struct diff_queued_diff;
diff --git a/diff.h b/diff.h
index 0d1f9ae347..6c25023746 100644
--- a/diff.h
+++ b/diff.h
@@ -28,11 +28,8 @@ extern void diff_unmerge(const char *path);
 
 extern int diff_scoreopt_parse(const char *opt);
 
-#define DIFF_FORMAT_HUMAN	0
-#define DIFF_FORMAT_MACHINE	1
-#define DIFF_FORMAT_PATCH	2
-#define DIFF_FORMAT_NO_OUTPUT	3
-extern void diff_setup(int reverse);
+#define DIFF_SETUP_REVERSE      	1
+extern void diff_setup(int flags);
 
 #define DIFF_DETECT_RENAME	1
 #define DIFF_DETECT_COPY	2
@@ -44,6 +41,11 @@ extern void diffcore_pathspec(const char **pathspec);
 
 extern int diff_queue_is_empty(void);
 
+#define DIFF_FORMAT_HUMAN	0
+#define DIFF_FORMAT_MACHINE	1
+#define DIFF_FORMAT_PATCH	2
+#define DIFF_FORMAT_NO_OUTPUT	3
+
 extern void diff_flush(int output_style, int resolve_rename_copy);
 
 #endif /* DIFF_H */