diff --git a/requirements.txt b/requirements.txt
index b1d4872..5f2fff3 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -5,4 +5,6 @@
 #
 # Build requirements
 charm-tools>=2.4.4
+# importlib-resources 1.1.0 removed Python 3.5 support
+importlib-resources<1.1.0
 simplejson