diff --git a/pymisp/abstract.py b/pymisp/abstract.py
index 8a4be01..88198af 100644
--- a/pymisp/abstract.py
+++ b/pymisp/abstract.py
@@ -247,8 +247,9 @@ class AbstractMISP(MutableMapping, MISPFileCache, metaclass=ABCMeta):
                 option |= orjson.OPT_SORT_KEYS
             if indent:
                 option |= orjson.OPT_INDENT_2
-
-            return dumps(self, default=pymisp_json_default, option=option).decode("utf-8")
+            # orjson dumps method returns bytes instead of bytes, to keep compatibility with json
+            # we have to convert output to str
+            return str(dumps(self, default=pymisp_json_default, option=option))
 
         return dumps(self, default=pymisp_json_default, sort_keys=sort_keys, indent=indent)