diff --git a/tei2json/requirements.txt b/tei2json/requirements.txt
index dbb06c7..fc78ed7 100644
--- a/tei2json/requirements.txt
+++ b/tei2json/requirements.txt
@@ -82,7 +82,7 @@ testpath==0.4.4
 text-unidecode==1.3
 tornado==6.0.4
 traitlets==4.3.3
-ujson==1.35
+ujson==5.2.0
 urllib3==1.25.7
 uvicorn==0.11.7
 uvloop==0.14.0