diff --git a/requirements.txt b/requirements.txt
index 6480df4..2394c05 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -10,7 +10,7 @@ setuptools<50.0.0  # https://github.com/pypa/setuptools/commit/04e3df22df840c6bb
 
 # Build requirements
 cffi==1.14.6; python_version < '3.6'  # cffi 1.15.0 drops support for py35.
-charm-tools==2.8.3; python_version < '3.10'
+charm-tools==2.8.5; python_version < '3.10'
 charm-tools; python_version >= '3.10'
 
 simplejson
diff --git a/tox.ini b/tox.ini
index a25f869..ab5d020 100644
--- a/tox.ini
+++ b/tox.ini
@@ -33,7 +33,7 @@ allowlist_externals =
     charmcraft
     bash
     tox
-    rename.sh
+    {toxinidir}/rename.sh
 deps =
     -r{toxinidir}/requirements.txt