diff --git a/requirements.txt b/requirements.txt
index 39a2b0268d..193c64e711 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -25,5 +25,6 @@ cryptography>=1.6
 cachecontrol
 pyjwt
 iso8601
+yarl>=0.11,<1.0
 aiohttp
 uvloop;python_version>='3.5'