diff --git a/requirements.txt b/requirements.txt
index 41f4a2f9..dc77daab 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -12,4 +12,4 @@ ttfautohint-py==0.5.1
 
 # optional, for experimental reading/writing ufoLib2's UFO as json
 cattrs==23.1.2
-orjson==3.9.3; platform_python_implementation == 'CPython'
+orjson==3.9.9; platform_python_implementation == 'CPython'