diff --git a/tools/requirements.txt b/tools/requirements.txt
index 5befef9a8..920343fad 100644
--- a/tools/requirements.txt
+++ b/tools/requirements.txt
@@ -2,3 +2,6 @@ logbook
 structlog
 taskcluster
 raven
+
+# Limit yarl version to avoid using the alpha 1.4.0a that breaks builds
+yarl==1.3.0