diff --git a/qutebrowser/utils/utils.py b/qutebrowser/utils/utils.py
index 632773b7f..f6b1d5a9f 100644
--- a/qutebrowser/utils/utils.py
+++ b/qutebrowser/utils/utils.py
@@ -895,4 +895,7 @@ def yaml_dump(data, f=None):
     """
     yaml_data = yaml.dump(data, f, Dumper=YamlDumper, default_flow_style=False,
                           encoding='utf-8', allow_unicode=True)
-    return yaml_data.decode('utf-8')
+    if yaml_data is None:
+        return None
+    else:
+        return yaml_data.decode('utf-8')
diff --git a/tests/unit/utils/test_utils.py b/tests/unit/utils/test_utils.py
index d5585c06e..4bec8f57c 100644
--- a/tests/unit/utils/test_utils.py
+++ b/tests/unit/utils/test_utils.py
@@ -938,9 +938,22 @@ def test_expand_windows_drive(path, expected):
     assert utils.expand_windows_drive(path) == expected
 
 
-def test_yaml_load():
-    assert utils.yaml_load("[1, 2]") == [1, 2]
+class TestYaml:
 
+    def test_load(self):
+        assert utils.yaml_load("[1, 2]") == [1, 2]
 
-def test_yaml_dump():
-    assert utils.yaml_dump([1, 2]) == '- 1\n- 2\n'
+    def test_load_file(self, tmpdir):
+        tmpfile = tmpdir / 'foo.yml'
+        tmpfile.write('[1, 2]')
+        with tmpfile.open(encoding='utf-8') as f:
+            assert utils.yaml_load(f) == [1, 2]
+
+    def test_dump(self):
+        assert utils.yaml_dump([1, 2]) == '- 1\n- 2\n'
+
+    def test_dump_file(self, tmpdir):
+        tmpfile = tmpdir / 'foo.yml'
+        with tmpfile.open('w', encoding='utf-8') as f:
+            utils.yaml_dump([1, 2], f)
+        assert tmpfile.read() == '- 1\n- 2\n'