diff --git a/cache.h b/cache.h
index 6049f86711..7bd7c472f8 100644
--- a/cache.h
+++ b/cache.h
@@ -1193,6 +1193,7 @@ extern int get_oid_hex(const char *hex, struct object_id *sha1);
  *   printf("%s -> %s", sha1_to_hex(one), sha1_to_hex(two));
  */
 extern char *sha1_to_hex_r(char *out, const unsigned char *sha1);
+extern char *oid_to_hex_r(char *out, const struct object_id *oid);
 extern char *sha1_to_hex(const unsigned char *sha1);	/* static buffer result! */
 extern char *oid_to_hex(const struct object_id *oid);	/* same static buffer as sha1_to_hex */
 
diff --git a/hex.c b/hex.c
index 0519f853b2..9619b67af0 100644
--- a/hex.c
+++ b/hex.c
@@ -77,6 +77,11 @@ char *sha1_to_hex_r(char *buffer, const unsigned char *sha1)
 	return buffer;
 }
 
+char *oid_to_hex_r(char *buffer, const struct object_id *oid)
+{
+	return sha1_to_hex_r(buffer, oid->hash);
+}
+
 char *sha1_to_hex(const unsigned char *sha1)
 {
 	static int bufno;