diff --git a/requirements.txt b/requirements.txt
index f9bfb48a31e1d9eeea6f2b0971860b41153caa18..2bc7e63f4704bdabe6d3ed5e4ad35290ddc4aa4b 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -1,3 +1,3 @@
 web.py>=0.50,<0.60
 gdal<2.5.0
-pyyaml
+pyyaml<5.4