diff --git a/requirements_dev.txt b/requirements_dev.txt
index 4247b48..2d5189a 100644
--- a/requirements_dev.txt
+++ b/requirements_dev.txt
@@ -10,4 +10,4 @@ docker-compose==1.26.2;python_version<"3.5"
 pathlib2==2.3.5;python_version<"3.4"
 
 # indirect dependencies
-pyrsistent<0.17.0;python_version<"3.5"
+pyrsistent==0.20.0;python_version<"3.5"