diff --git a/biosimulators_utils/_version.py b/biosimulators_utils/_version.py
index 112abf13..ac1125f5 100644
--- a/biosimulators_utils/_version.py
+++ b/biosimulators_utils/_version.py
@@ -1 +1 @@
-__version__ = '0.1.14'
+__version__ = '0.1.15'
diff --git a/biosimulators_utils/image.py b/biosimulators_utils/image.py
index 780935dc..63facced 100644
--- a/biosimulators_utils/image.py
+++ b/biosimulators_utils/image.py
@@ -35,16 +35,16 @@ def login_to_docker_registry(registry, username, password):
     return docker_client
 
 
-def pull_docker_image(url):
+def pull_docker_image(docker_client, url):
     """ Pull Docker image
 
     Args:
+        docker_client (:obj:`docker.client.DockerClient`): Docker client
         url (:obj:`str`): URL for Docker image
 
     Returns:
         :obj:`docker.models.images.Image`: Docker image
     """
-    docker_client = docker.from_env()
     try:
         return docker_client.images.pull(url)
     except docker.errors.NotFound:
@@ -54,15 +54,15 @@ def pull_docker_image(url):
             url, str(error).replace('\n', '\n  ')))
 
 
-def tag_and_push_docker_image(image, tag):
+def tag_and_push_docker_image(docker_client, image, tag):
     """ Tag and push Docker image
 
     Args:
+        docker_client (:obj:`docker.client.DockerClient`): Docker client
         image (:obj:`docker.models.images.Image`): Docker image
         tag (:obj:`str`): tag
     """
     assert image.tag(tag)
-    docker_client = docker.from_env()
     response = docker_client.images.push(tag)
     response = json.loads(response.rstrip().split('\n')[-1])
     if 'error' in response:
diff --git a/tests/test_image.py b/tests/test_image.py
index 81e4f67f..b06300e0 100644
--- a/tests/test_image.py
+++ b/tests/test_image.py
@@ -19,26 +19,26 @@ def test_pull_docker_image(self):
             'docker.io',
             os.getenv("DOCKER_HUB_USERNAME"),
             os.getenv("DOCKER_HUB_TOKEN"))
-        image.pull_docker_image('hello-world')
+        image.pull_docker_image(docker_client, 'hello-world')
 
         with self.assertRaises(docker.errors.NotFound):
-            image.pull_docker_image('hello-undefined')
+            image.pull_docker_image(docker_client, 'hello-undefined')
 
         with self.assertRaises(Exception):
-            image.pull_docker_image('---undefined---')
+            image.pull_docker_image(docker_client, '---undefined---')
 
     def test_tag_and_push_docker_image(self):
         docker_client = image.login_to_docker_registry(
             'docker.io',
             os.getenv("DOCKER_HUB_USERNAME"),
             os.getenv("DOCKER_HUB_TOKEN"))
-        img = image.pull_docker_image('hello-world')
+        img = image.pull_docker_image(docker_client, 'hello-world')
 
         response = '{"error": "x"}'
         docker_client = mock.Mock(images=mock.Mock(push=lambda tag: response))
         with mock.patch('docker.from_env', return_value=docker_client):
             with self.assertRaisesRegex(Exception, 'Unable to push image to'):
-                image.tag_and_push_docker_image(img, 'hello-world-2')
+                image.tag_and_push_docker_image(docker_client, img, 'hello-world-2')
 
     def test_convert_docker_image_to_singularity(self):
         filename = image.convert_docker_image_to_singularity('hello-world')