diff --git a/setup.py b/setup.py
index bf08290..cf6ef6c 100644
--- a/setup.py
+++ b/setup.py
@@ -2,7 +2,7 @@
 ################################################################################
 #
 #  Rattail -- Retail Software Framework
-#  Copyright © 2010-2021 Lance Edgar
+#  Copyright © 2010-2022 Lance Edgar
 #
 #  This file is part of Rattail.
 #
@@ -62,6 +62,10 @@ requires = [
     #
     # package                           # low                   high
 
+    # TODO: v1.1 suddenly caused an issue; perhaps can remove this
+    # restriction once a later version comes out?
+    # cf. https://docs.pylonsproject.org/projects/plaster/en/latest/changes.html
+    'plaster<1.1',                      # 1.0
 ]