diff --git a/tests/test_files/smpl/alarm_citizen_loop1_udata.wav b/tests/test_files/smpl/alarm_citizen_loop1_udata.wav
new file mode 100644
index 0000000..08b0210
Binary files /dev/null and b/tests/test_files/smpl/alarm_citizen_loop1_udata.wav differ
diff --git a/wavinfo/__main__.py b/wavinfo/__main__.py
index 5dc1de9..a7a4de9 100644
--- a/wavinfo/__main__.py
+++ b/wavinfo/__main__.py
@@ -14,7 +14,7 @@ class MyJSONEncoder(json.JSONEncoder):
         if isinstance(o, Enum):
             return o._name_
         elif isinstance(o, bytes):
-            return b64encode(o).decode('ascii')
+            return 'base64:' + b64encode(o).decode('ascii')
         else:
             return super().default(o)