diff --git a/Dockerfile.template b/Dockerfile.template
index 3e77ec986..a0eec25b2 100644
--- a/Dockerfile.template
+++ b/Dockerfile.template
@@ -11,8 +11,9 @@ LABEL build-date-iso8601="${build_date}"
 
 WORKDIR /root
 
+# due https://github.com/moby/moby/issues/47021 we cannot have /root/.cache leftover as it causes random errors in CI
 RUN --mount=type=bind,source=${tar_path}/${tar_name},target=/tmp/${tar_name} \
-  pip install --no-cache-dir /tmp/${tar_name}[full]
+  pip install --no-cache-dir /tmp/${tar_name}[full] && rm -rf /root/.cache
 
 ENTRYPOINT ["b2"]
 CMD ["--help"]
diff --git a/b2/_internal/_cli/autocomplete_cache.py b/b2/_internal/_cli/autocomplete_cache.py
index 443f759a8..ca0e517d3 100644
--- a/b2/_internal/_cli/autocomplete_cache.py
+++ b/b2/_internal/_cli/autocomplete_cache.py
@@ -50,15 +50,14 @@ def current_state_identifier(self) -> str:
 class HomeCachePickleStore(PickleStore):
     _dir: pathlib.Path
 
-    def __init__(self, dir: pathlib.Path | None = None) -> None:
-        self._dir = dir
+    def __init__(self, dir_path: pathlib.Path | None = None) -> None:
+        self._dir = dir_path
 
     def _cache_dir(self) -> pathlib.Path:
-        if self._dir:
-            return self._dir
-        self._dir = pathlib.Path(
-            platformdirs.user_cache_dir(appname='b2', appauthor='backblaze')
-        ) / 'autocomplete'
+        if not self._dir:
+            self._dir = pathlib.Path(
+                platformdirs.user_cache_dir(appname='b2', appauthor='backblaze')
+            ) / 'autocomplete'
         return self._dir
 
     def _fname(self, identifier: str) -> str:
@@ -74,10 +73,10 @@ def set_pickle(self, identifier: str, data: bytes) -> None:
         """Sets the pickle for identifier if it doesn't exist.
         When a new pickle is added, old ones are removed."""
 
-        dir = self._cache_dir()
-        os.makedirs(dir, exist_ok=True)
-        path = dir / self._fname(identifier)
-        for file in dir.glob('b2-autocomplete-cache-*.pickle'):
+        dir_path = self._cache_dir()
+        dir_path.mkdir(parents=True, exist_ok=True)
+        path = dir_path / self._fname(identifier)
+        for file in dir_path.glob('b2-autocomplete-cache-*.pickle'):
             file.unlink()
         with open(path, 'wb') as f:
             f.write(data)
diff --git a/changelog.d/+docker_mkdir_fail.infrastructure.md b/changelog.d/+docker_mkdir_fail.infrastructure.md
new file mode 100644
index 000000000..d3750be17
--- /dev/null
+++ b/changelog.d/+docker_mkdir_fail.infrastructure.md
@@ -0,0 +1 @@
+Fix CI failing on `mkdir` when testing docker image.
diff --git a/noxfile.py b/noxfile.py
index d95fe7bee..b184a5443 100644
--- a/noxfile.py
+++ b/noxfile.py
@@ -609,11 +609,11 @@ def generate_dockerfile(session):
 
 def run_docker_tests(session, image_tag):
     """Run unittests against a docker image."""
+    docker_run_cmd = "docker run -i -v b2:/root/ -v /tmp:/tmp:rw --env-file ENVFILE"
     run_integration_test(
         session, [
             "--sut",
-            "docker run -i -v b2:/root -v /tmp:/tmp:rw "
-            f"--env-file ENVFILE {image_tag}",
+            f"{docker_run_cmd} {image_tag}",
             "--env-file-cmd-placeholder",
             "ENVFILE",
         ]
@@ -622,9 +622,7 @@ def run_docker_tests(session, image_tag):
         run_integration_test(
             session, [
                 "--sut",
-                "docker run -i -v b2:/root -v /tmp:/tmp:rw "
-                f"--entrypoint {binary_name} "
-                f"--env-file ENVFILE {image_tag}",
+                f"{docker_run_cmd} --entrypoint {binary_name} {image_tag}",
                 "--env-file-cmd-placeholder",
                 "ENVFILE",
             ]