diff --git a/CHANGELOG.md b/CHANGELOG.md
index 13b2544..26fd933 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -2,6 +2,10 @@
 
 Note: Breaking changes between versions are indicated by "💥".
 
+## Unreleased
+
+- [Bugfix] Fix `local exec` command which crashed with a `AttributeError`.
+
 ## v11.1.0 (2021-01-13)
 
 - [Bugfix] Fix "Read-only file system" errors when running `tutor dev runserver` commands on Mac OS. (again, see #392)
diff --git a/tutor/bindmounts.py b/tutor/bindmounts.py
index f401bad..013922b 100644
--- a/tutor/bindmounts.py
+++ b/tutor/bindmounts.py
@@ -59,7 +59,7 @@ def get_root_path(root):
     return os.path.join(root, "volumes")
 
 
-def parse_volumes(args):
+def parse_volumes(docker_compose_args):
     """
     Parse `-v/--volume` options from an arbitrary list of arguments.
     """
@@ -70,5 +70,7 @@ def parse_volumes(args):
     def custom_docker_compose(volumes, args):  # pylint: disable=unused-argument
         pass
 
-    context = custom_docker_compose.make_context("custom", args)
+    if isinstance(docker_compose_args, tuple):
+        docker_compose_args = list(docker_compose_args)
+    context = custom_docker_compose.make_context("custom", docker_compose_args)
     return context.params["volumes"], context.params["args"]