diff --git a/requirements.txt b/requirements.txt
index 7394d61..f5e4be3 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -15,7 +15,7 @@ pdfrw==0.4
 Pillow==5.2.0
 pycparser==2.18
 Pyphen==0.9.5
-PyYAML==3.13
+PyYAML>=4.2b1
 six==1.11.0
 tinycss2==0.6.1
 tornado==5.1