diff --git a/tests/unit/requirements.txt b/tests/unit/requirements.txt
index bcd2edc9e3..30819a1a80 100644
--- a/tests/unit/requirements.txt
+++ b/tests/unit/requirements.txt
@@ -6,7 +6,8 @@ unittest2 ; python_version < '2.7'
 importlib ; python_version < '2.7'
 
 # requirement for the memcached cache plugin
-python-memcached
+python-memcached < 1.60 ; python_version < '3.6'
+python-memcached ; python_version >= '3.6'
 
 # requirement for the redis cache plugin
 redis