diff --git a/requirements.txt b/requirements.txt
index 003bc70..f23ee00 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -1,5 +1,5 @@
 # Hard pinning here gets relaxed to ">=" in setup.py
-afdko==3.9.7
+afdko==4.0.0
 fonttools==4.42.1
 brotli==1.1.0
 click==8.1.7