diff --git a/tildes/requirements-to-freeze.txt b/tildes/requirements-to-freeze.txt
index 2d56bd2..55e7f43 100644
--- a/tildes/requirements-to-freeze.txt
+++ b/tildes/requirements-to-freeze.txt
@@ -25,7 +25,7 @@ pyramid
 pyramid-debugtoolbar
 pyramid-ipython
 pyramid-jinja2
-pyramid-session-redis
+pyramid-session-redis==1.5.0  # 1.5.1 has a change that will invalidate current sessions
 pyramid-tm
 pyramid-webassets
 pytest