diff --git a/CI_REQUIREMENTS.txt b/CI_REQUIREMENTS.txt
index e989460..2d0cfe9 100644
--- a/CI_REQUIREMENTS.txt
+++ b/CI_REQUIREMENTS.txt
@@ -1,2 +1,4 @@
 -r requirements.txt
-lxml
+lxml!=3.7.0
+PyYAML>=3.12
+ruamel.yaml
diff --git a/README.rst b/README.rst
index c8594e0..6a19c93 100644
--- a/README.rst
+++ b/README.rst
@@ -223,7 +223,7 @@ Execution result object has a set of useful properties:
 
 * `stdout_json` - STDOUT decoded as JSON.
 
-* `stdout_yaml` - STDOUT decoded as YAML.
+* `stdout_yaml` - STDOUT decoded as YAML. Accessible only if PyYAML or ruamel.YAML library installed.
 
 * `stdout_xml` - STDOUT decoded as XML to `ElementTree` using `defusedxml` library.
 
diff --git a/doc/source/ExecResult.rst b/doc/source/ExecResult.rst
index 46ddf2a..50eb223 100644
--- a/doc/source/ExecResult.rst
+++ b/doc/source/ExecResult.rst
@@ -146,6 +146,7 @@ API: ExecResult
 
         :rtype: ``typing.Any``
         :raises DeserializeValueError: STDOUT can not be deserialized as YAML
+        :raises AttributeError: no any yaml parser installed
 
     .. py:attribute:: stdout_xml
 
diff --git a/exec_helpers/exec_result.py b/exec_helpers/exec_result.py
index e294188..ee5d95d 100644
--- a/exec_helpers/exec_result.py
+++ b/exec_helpers/exec_result.py
@@ -28,13 +28,23 @@
 
 # External Dependencies
 import defusedxml.ElementTree  # type: ignore
-import yaml
 
 # Exec-Helpers Implementation
 from exec_helpers import exceptions
 from exec_helpers import proc_enums
 
 try:
+    # noinspection PyPackageRequirements
+    import yaml
+except ImportError:
+    yaml = None  # type:ignore  # pylint: disable=invalid-name
+try:
+    import ruamel.yaml as ruamel_yaml  # type: ignore
+except ImportError:
+    ruamel_yaml = None  # pylint: disable=invalid-name
+
+try:
+    # noinspection PyPackageRequirements
     import lxml.etree  # type: ignore  # nosec
 except ImportError:
     lxml = None  # pylint: disable=invalid-name
@@ -496,9 +506,11 @@ def __deserialize(self, fmt: str) -> typing.Any:
             if fmt == "json":
                 return json.loads(self.stdout_str, encoding="utf-8")
             if fmt == "yaml":
-                if yaml.__with_libyaml__:
-                    return yaml.load(self.stdout_str, Loader=yaml.CSafeLoader)  # nosec  # Safe
-                return yaml.safe_load(self.stdout_str)
+                if yaml is not None:
+                    if yaml.__with_libyaml__:
+                        return yaml.load(self.stdout_str, Loader=yaml.CSafeLoader)  # nosec  # Safe
+                    return yaml.safe_load(self.stdout_str)
+                return ruamel_yaml.YAML(typ="safe").load(self.stdout_str)  # nosec  # Safe
             if fmt == "xml":
                 return defusedxml.ElementTree.fromstring(bytes(self.stdout_bin))
             if fmt == "lxml":
@@ -531,7 +543,10 @@ def stdout_yaml(self) -> typing.Any:
 
         :rtype: typing.Any
         :raises DeserializeValueError: STDOUT can not be deserialized as YAML
+        :raises AttributeError: no any yaml parser installed
         """
+        if yaml is None and ruamel_yaml is None:
+            raise AttributeError("no any yaml parser installed -> attribute is not functional.")
         with self.stdout_lock:
             return self.__deserialize(fmt="yaml")
 
@@ -576,10 +591,11 @@ def __dir__(self) -> typing.List[str]:
             "stdout_lines",
             "stderr_lines",
             "stdout_json",
-            "stdout_yaml",
             "stdout_xml",
             "lock",
         ]
+        if yaml is not None or ruamel_yaml is not None:
+            content.append("stdout_yaml")
         if lxml is not None:
             content.append("stdout_lxml")
         return content
diff --git a/requirements.txt b/requirements.txt
index ec5a37d..348e598 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -2,7 +2,6 @@ paramiko>=2.4  # LGPLv2.1+
 tenacity>=4.4.0  # Apache-2.0
 six>=1.10.0  # MIT
 threaded>=2.0  # Apache-2.0
-PyYAML>=3.12  # MIT
 advanced-descriptors>=1.0  # Apache-2.0
 typing >= 3.6 ; python_version < "3.7"  # PSF
 psutil >= 5.0  # BSD
diff --git a/setup.cfg b/setup.cfg
index 43c9ac2..2f6e3bd 100644
--- a/setup.cfg
+++ b/setup.cfg
@@ -66,6 +66,7 @@ ignore =
 # 1 blank line required before class docstring
   D213
 # Multi-line docstring summary should start at the second line
+match = (?!_version|test_)*.py
 
 [doc8]
 max-line-length = 150
diff --git a/setup.py b/setup.py
index 295581e..1e39587 100644
--- a/setup.py
+++ b/setup.py
@@ -259,7 +259,8 @@ def get_simple_vars_from_src(src):
     use_scm_version={'write_to': 'exec_helpers/_version.py'},
     install_requires=REQUIRED,
     extras_require={
-        "lxml": ["lxml!=3.7.0"]
+        "lxml": ["lxml!=3.7.0"],
+        "yaml": ["PyYAML>=3.12"],
     },
     package_data={"exec_helpers": ["py.typed"]},
 )
diff --git a/test/test_exec_result.py b/test/test_exec_result.py
index 6a72d33..8e82738 100644
--- a/test/test_exec_result.py
+++ b/test/test_exec_result.py
@@ -26,6 +26,14 @@
 import exec_helpers
 from exec_helpers import proc_enums
 
+try:
+    import yaml
+except ImportError:
+    yaml = None
+try:
+    import ruamel.yaml as ruamel_yaml
+except ImportError:
+    ruamel_yaml = None
 try:
     import lxml.etree
 except ImportError:
@@ -79,7 +87,6 @@ def test_create_minimal(self, logger):
             # noinspection PyStatementEffect
             result["stdout_json"]  # pylint: disable=pointless-statement
         logger.assert_has_calls((mock.call.exception(f"{cmd} stdout is not valid json:\n{result.stdout_str!r}\n"),))
-        self.assertIsNone(result["stdout_yaml"])
 
         self.assertEqual(hash(result), hash((exec_helpers.ExecResult, cmd, None, (), (), proc_enums.INVALID)))
 
@@ -149,7 +156,6 @@ def test_wrong_result(self, logger):
             # noinspection PyStatementEffect
             result.stdout_json  # pylint: disable=pointless-statement
         logger.assert_has_calls((mock.call.exception(f"{cmd} stdout is not valid json:\n{result.stdout_str!r}\n"),))
-        self.assertIsNone(result["stdout_yaml"])
 
     def test_not_equal(self):
         """Exec result equality is validated by all fields."""
@@ -294,3 +300,35 @@ def test_stdout_lxml(self):
         self.assertEqual(
             lxml.etree.tostring(expect), lxml.etree.tostring(result.stdout_lxml)
         )
+
+    @unittest.skipUnless(yaml is not None, "PyYAML parser should be installed")
+    def test_stdout_yaml_pyyaml(self):
+        result = exec_helpers.ExecResult(
+            "test",
+            stdout=[
+                b"{test: data}\n"
+            ]
+        )
+        expect = {"test": "data"}
+        self.assertEqual(expect, result.stdout_yaml)
+
+
+# noinspection PyTypeChecker
+class TestExecResultRuamelYaml(unittest.TestCase):
+    def setUp(self) -> None:
+        self._orig_yaml, exec_helpers.exec_result.yaml = exec_helpers.exec_result.yaml, None
+
+    def tearDown(self) -> None:
+        exec_helpers.exec_result.yaml = self._orig_yaml
+
+    @unittest.skipUnless(ruamel_yaml is not None, "Ruamel.YAML parser should be installed")
+    def test_stdout_yaml_ruamel(self):
+        result = exec_helpers.ExecResult(
+            "test",
+            stdout=[
+                b"{test: data}\n"
+            ]
+        )
+        expect = {"test": "data"}
+        result = result.stdout_yaml
+        self.assertEqual(expect, result)
diff --git a/tox.ini b/tox.ini
index 8e963f1..2b0e2d5 100644
--- a/tox.ini
+++ b/tox.ini
@@ -108,7 +108,6 @@ commands = pipdeptree
 [testenv:mypy]
 deps =
   mypy>=0.700
-  lxml
   -r{toxinidir}/CI_REQUIREMENTS.txt
 commands =
   python setup.py --version