diff --git a/.travis.yml b/.travis.yml
index 5b1b3e6..2abed05 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -16,6 +16,11 @@ matrix:
       env: TOXENV=py-base
     - python: "3.6"
       env: TOXENV=py-base
+    - # TODO: Remove this workaround once travis-ci/travis-ci#9815 is fixed.
+      sudo: true
+      dist: xenial
+      python: "3.7"
+      env: TOXENV=py-s3
 
 cache:
   directories:
diff --git a/flask_annex/compat.py b/flask_annex/compat.py
index 0c4806a..ef8d3c2 100644
--- a/flask_annex/compat.py
+++ b/flask_annex/compat.py
@@ -24,5 +24,5 @@ def recursive_glob(root_dir, pattern='*'):
     return tuple(
         os.path.join(root, filename)
         for root, _dirnames, filenames in os.walk(root_dir)
-        for filename in fnmatch.filter(filenames, pattern),
+        for filename in fnmatch.filter(filenames, pattern)
     )
diff --git a/flask_annex/file.py b/flask_annex/file.py
index 9156adc..046fd88 100644
--- a/flask_annex/file.py
+++ b/flask_annex/file.py
@@ -61,7 +61,7 @@ def list_keys(self, prefix):
 
         return tuple(
             os.path.relpath(filename, self._root_path)
-            for filename in filenames,
+            for filename in filenames
         )
 
     def save_file(self, key, in_file):
diff --git a/tox.ini b/tox.ini
index 755eb19..bfbe0ef 100644
--- a/tox.ini
+++ b/tox.ini
@@ -1,5 +1,5 @@
 [tox]
-envlist = py{27,35,36}-{base,s3}
+envlist = py{27,35,36,37}-{base,s3}
 
 [testenv]
 usedevelop = True