diff --git a/setup.py b/setup.py
index bf9b59f5..5154c60a 100755
--- a/setup.py
+++ b/setup.py
@@ -82,7 +82,7 @@ params = dict(
         'pexpect>=3.3',  # Send/receive to/from device
         'pyserial',  # Serial port interface
         'colorama',  # Printing with colors
-        'pyYAML',  # YAML-formatted agenda parsing
+        'pyYAML<=3.13',  # YAML-formatted agenda parsing
         'requests',  # Fetch assets over HTTP
         'devlib>={}'.format(format_version(required_devlib_version)),  # Interacting with devices
         'louie-latest',  # callbacks dispatch