diff --git a/dox/config/dox_yaml.py b/dox/config/dox_yaml.py
index 88f890b..a08a9cd 100644
--- a/dox/config/dox_yaml.py
+++ b/dox/config/dox_yaml.py
@@ -37,7 +37,8 @@ class DoxYaml(object):
 
     def _open_dox_yaml(self):
         if self._yaml is None:
-            self._yaml = yaml.load(open('dox.yml', 'r'))
+            with open('dox.yml', 'r') as f:
+                self._yaml = yaml.load(f)
         return self._yaml
 
     def exists(self):
diff --git a/dox/config/travis_yaml.py b/dox/config/travis_yaml.py
index df0482c..60bffe9 100644
--- a/dox/config/travis_yaml.py
+++ b/dox/config/travis_yaml.py
@@ -37,7 +37,8 @@ class TravisYaml(object):
 
     def _open_travis_yaml(self):
         if self._yaml is None:
-            self._yaml = yaml.load(open('travis.yml', 'r'))
+            with open('travis.yml', 'r') as f:
+                self._yaml = yaml.load(f)
         return self._yaml
 
     def exists(self):
diff --git a/dox/runner.py b/dox/runner.py
index 2264648..37c470c 100644
--- a/dox/runner.py
+++ b/dox/runner.py
@@ -138,7 +138,8 @@ class Runner(object):
             for command in commands.prep_commands():
                 dockerfile.append("RUN %s\n" % command)
             dockerfile = '\n'.join(dockerfile)
-            open(os.path.join(tempd, 'Dockerfile'), 'w').write(dockerfile)
+            with open(os.path.join(tempd, 'Dockerfile'), 'w') as f:
+                f.write(dockerfile)
             logger.debug("Dockerfile:\n" + self._indent(dockerfile))
             self._docker_build(self.test_image_name, tempd)
         finally: