diff --git a/.github/workflows/main.yml b/.github/workflows/main.yml
index 82dacff8..55ef30bd 100644
--- a/.github/workflows/main.yml
+++ b/.github/workflows/main.yml
@@ -53,7 +53,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        python-version: ["3.7"]
+        python-version: ["3.7", "3.9"]
     steps:
       - uses: actions/checkout@v2
       #setup miniconda
diff --git a/stytra/utilities.py b/stytra/utilities.py
index 731a10d3..b1adcc26 100644
--- a/stytra/utilities.py
+++ b/stytra/utilities.py
@@ -239,7 +239,7 @@ def recursive_update(d, u):
     :return:
     """
     for k, v in u.items():
-        if isinstance(v, collections.Mapping):
+        if isinstance(v, collections.abc.Mapping):
             d[k] = recursive_update(d.get(k, {}), v)
         else:
             d[k] = v