--- a/taskcluster/taskgraph/task/docker_image.py
+++ b/taskcluster/taskgraph/task/docker_image.py
@@ -138,17 +138,17 @@ class DockerImageTask(base.Task):
         """Creates a tar file of a particular context directory.
 
         Returns the SHA-256 hex digest of the created file.
         """
         destination = os.path.abspath(destination)
         if not os.path.exists(os.path.dirname(destination)):
             os.makedirs(os.path.dirname(destination))
 
-        return create_context_tar(context_dir, destination, image_name)
+        return create_context_tar(GECKO, context_dir, destination, image_name)
 
     @classmethod
     def from_json(cls, task_dict):
         # Generating index_paths for optimization
         routes = task_dict['task']['routes']
         index_paths = []
         for route in routes:
             index_path_regex = re.compile(INDEX_REGEX)

--- a/taskcluster/taskgraph/util/docker.py
+++ b/taskcluster/taskgraph/util/docker.py
@@ -55,17 +55,17 @@ def generate_context_hash(image_path):
             file_hash = hashlib.sha256()
             data = f.read()
             file_hash.update(data)
             context_hash.update(file_hash.hexdigest() + '\t' + relative_filename + '\n')
 
     return context_hash.hexdigest()
 
 
-def create_context_tar(context_dir, out_path, prefix):
+def create_context_tar(topsrcdir, context_dir, out_path, prefix):
     """Create a context tarball.
 
     A directory ``context_dir`` containing a Dockerfile will be assembled into
     a gzipped tar file at ``out_path``. Files inside the archive will be
     prefixed by directory ``prefix``.
 
     Returns the SHA-256 hex digest of the created archive.
     """