diff --git a/json_object.c b/json_object.c
index 482c5e3..bc09d65 100644
--- a/json_object.c
+++ b/json_object.c
@@ -32,7 +32,7 @@
 /* #define REFCOUNT_DEBUG 1 */
 
 const char *json_number_chars = "0123456789.+-eE";
-const char *json_hex_chars = "0123456789abcdef";
+const char *json_hex_chars = "0123456789abcdefABCDEF";
 
 static void json_object_generic_delete(struct json_object* jso);
 static struct json_object* json_object_new(enum json_type o_type);