diff --git a/artifactory_cleanup/__init__.py b/artifactory_cleanup/__init__.py
index 2246c34..7279cb8 100644
--- a/artifactory_cleanup/__init__.py
+++ b/artifactory_cleanup/__init__.py
@@ -7,4 +7,4 @@ def register(rule):
     registry.register(rule)
 
 
-__version__ = "1.0.3"
+__version__ = "1.0.4"
diff --git a/artifactory_cleanup/rules/keep.py b/artifactory_cleanup/rules/keep.py
index a08c4f9..28e989a 100644
--- a/artifactory_cleanup/rules/keep.py
+++ b/artifactory_cleanup/rules/keep.py
@@ -158,7 +158,7 @@ def filter(self, artifacts):
                 version_str = (
                     version[0][0] if isinstance(version[0], tuple) else version[0]
                 )
-                artifactory_with_version = [version_str, artifact]
+                artifactory_with_version = (version_str, artifact)
                 name_without_version = artifact["name"][
                     : artifact["name"].find(version_str)
                 ]
@@ -173,9 +173,8 @@ def filter(self, artifacts):
                 artifacts.keep(artifact)
 
         for artifactory_with_version in artifacts_by_path_and_name.values():
-            artifactory_with_version.sort(
-                key=lambda x: [int(x) for x in x[0].split(".")]
-            )
+            # List of pairs: [version, ArtifactDict]
+            artifactory_with_version.sort(key=lambda pair: pair[0])
 
             artifact_count = len(artifactory_with_version)
             good_artifact_count = artifact_count - self.count
diff --git a/setup.py b/setup.py
index 3c964e7..578cab3 100644
--- a/setup.py
+++ b/setup.py
@@ -12,7 +12,7 @@
 
 setup(
     name="artifactory-cleanup",
-    version="1.0.3",
+    version="1.0.4",
     description="Rules and cleanup policies for Artifactory",
     long_description=long_description,
     long_description_content_type="text/markdown",
diff --git a/tests/test_rules_keep.py b/tests/test_rules_keep.py
index d6cb557..4840a0a 100644
--- a/tests/test_rules_keep.py
+++ b/tests/test_rules_keep.py
@@ -7,215 +7,252 @@
 from tests.utils import makeas
 
 
-def test_KeepLatestNFiles():
-    data = [
-        {
-            "path": "2.1.1",
-            "name": "name.zip",
-            "created": "2021-03-20T13:54:52.383+02:00",
-        },
-        {
-            "path": "0.1.100",
-            "name": "name.zip",
-            "created": "2021-03-19T13:53:52.383+02:00",
-        },
-        {
-            "path": "0.1.200",
-            "name": "name.zip",
-            "created": "2021-01-19T13:53:52.383+02:00",
-        },
-        {
-            "path": "0.1.99",
-            "name": "name.zip",
-            "created": "2021-01-19T13:53:52.383+02:00",
-        },
-        {
-            "path": "1.3.1",
-            "name": "name.zip",
-            "created": "2021-03-20T13:53:52.383+02:00",
-        },
-    ]
-
-    artifacts = ArtifactsList.from_response(data)
-
-    remove_these = KeepLatestNFiles(2).filter(artifacts)
-    expected = [
-        {
-            "path": "0.1.200",
-        },
-        {
-            "path": "0.1.99",
-        },
-        {
-            "path": "0.1.100",
-        },
-    ]
-    assert makeas(remove_these, expected) == expected
-
-
-def test_KeepLatestNFilesInFolder():
-    data = [
-        {
-            "path": "folder1",
-            "name": "0.0.2.zip",
-            "created": "2021-03-20T13:54:52.383+02:00",
-        },
-        {
-            "path": "folder1",
-            "name": "0.0.1.zip",
-            "created": "2021-03-19T13:53:52.383+02:00",
-        },
-        {
-            "path": "folder2",
-            "name": "0.0.1.zip",
-            "created": "2021-03-19T13:53:52.383+02:00",
-        },
-        {
-            "path": "folder2",
-            "name": "0.0.2.zip",
-            "created": "2021-03-20T13:54:52.383+02:00",
-        },
-        {
-            "path": "folder3",
-            "name": "0.0.1.zip",
-            "created": "2021-03-20T13:54:52.383+02:00",
-        },
-    ]
-
-    artifacts = ArtifactsList.from_response(data)
-
-    remove_these = KeepLatestNFilesInFolder(1).filter(artifacts)
-    expected = [
-        {"name": "0.0.1.zip", "path": "folder1"},
-        {"name": "0.0.1.zip", "path": "folder2"},
-    ]
-    assert makeas(remove_these, expected) == expected
-
-
-def test_KeepLatestVersionNFilesInFolderDefault():
-    data = [
-        {
-            "path": "folder1",
-            "name": "0.0.2.zip",
-            "created": "2021-03-20T13:54:52.383+02:00",
-        },
-        {
-            "path": "folder1",
-            "name": "0.0.1.zip",
-            "created": "2021-03-19T13:53:52.383+02:00",
-        },
-        {
-            "path": "folder2",
-            "name": "0.0.1.zip",
-            "created": "2021-03-20T13:54:52.383+02:00",
-        },
-        {
-            "path": "folder2",
-            "name": "0.0.2.zip",
-            "created": "2021-03-19T13:53:52.383+02:00",
-        },
-        {
-            "path": "folder3",
-            "name": "0.0.1.zip",
-            "created": "2021-03-20T13:54:52.383+02:00",
-        },
-    ]
-
-    artifacts = ArtifactsList.from_response(data)
-
-    remove_these = KeepLatestVersionNFilesInFolder(1).filter(artifacts)
-    expected = [
-        {"name": "0.0.1.zip", "path": "folder1"},
-        {"name": "0.0.1.zip", "path": "folder2"},
-    ]
-    assert makeas(remove_these, expected) == expected
-
-
-def test_KeepLatestVersionNFilesInFolderRegexWork():
-    data = [
-        {
-            "path": "folder1",
-            "name": "0.0.2.zip",
-            "created": "2021-03-20T13:54:52.383+02:00",
-        },
-        {
-            "path": "folder1",
-            "name": "0.0.1.zip",
-            "created": "2021-03-19T13:53:52.383+02:00",
-        },
-        {
-            "path": "folder2",
-            "name": "0.0.1.zip",
-            "created": "2021-03-20T13:54:52.383+02:00",
-        },
-        {
-            "path": "folder2",
-            "name": "0.0.2.zip",
-            "created": "2021-03-19T13:53:52.383+02:00",
-        },
-        {
-            "path": "folder3",
-            "name": "0.0.1.zip",
-            "created": "2021-03-20T13:54:52.383+02:00",
-        },
-        {
-            "path": "folder3",
-            "name": "1.0.1.zip",
-            "created": "2021-03-21T13:54:52.383+02:00",
-        },
-        {
-            "path": "folder3",
-            "name": "1.0.2.zip",
-            "created": "2021-03-21T14:54:52.383+02:00",
-        },
-    ]
-
-    artifacts = ArtifactsList.from_response(data)
-
-    remove_these = KeepLatestVersionNFilesInFolder(
-        1, "[\\d]+\\.([\\d]+\\.[\\d]+)"
-    ).filter(artifacts)
-    expected = [
-        {"name": "0.0.1.zip", "path": "folder1"},
-        {"name": "0.0.1.zip", "path": "folder2"},
-        {"name": "1.0.1.zip", "path": "folder3"},
-    ]
-    assert makeas(remove_these, expected) == expected
-
-
-def test_KeepLatestVersionNFilesInFolderRegexFail():
-    data = [
-        {
-            "path": "folder1",
-            "name": "0.0.2.zip",
-            "created": "2021-03-20T13:54:52.383+02:00",
-        },
-        {
-            "path": "folder1",
-            "name": "0.0.1.zip",
-            "created": "2021-03-19T13:53:52.383+02:00",
-        },
-        {
-            "path": "folder2",
-            "name": "0.0.1.zip",
-            "created": "2021-03-20T13:54:52.383+02:00",
-        },
-        {
-            "path": "folder2",
-            "name": "0.0.2.zip",
-            "created": "2021-03-19T13:53:52.383+02:00",
-        },
-        {
-            "path": "folder3",
-            "name": "0.0.1.zip",
-            "created": "2021-03-20T13:54:52.383+02:00",
-        },
-    ]
-
-    artifacts = ArtifactsList.from_response(data)
-
-    remove_these = KeepLatestVersionNFilesInFolder(
-        1, "[^\\d][\\._]((\\d+\\.)+\\d+)"
-    ).filter(artifacts)
-    expected = []
-    assert makeas(remove_these, expected) == expected
+class TestKeepLatestNFiles:
+    def test_basic_case(self):
+        data = [
+            {
+                "path": "2.1.1",
+                "name": "name.zip",
+                "created": "2021-03-20T13:54:52.383+02:00",
+            },
+            {
+                "path": "0.1.100",
+                "name": "name.zip",
+                "created": "2021-03-19T13:53:52.383+02:00",
+            },
+            {
+                "path": "0.1.200",
+                "name": "name.zip",
+                "created": "2021-01-19T13:53:52.383+02:00",
+            },
+            {
+                "path": "0.1.99",
+                "name": "name.zip",
+                "created": "2021-01-19T13:53:52.383+02:00",
+            },
+            {
+                "path": "1.3.1",
+                "name": "name.zip",
+                "created": "2021-03-20T13:53:52.383+02:00",
+            },
+        ]
+
+        artifacts = ArtifactsList.from_response(data)
+
+        remove_these = KeepLatestNFiles(2).filter(artifacts)
+        expected = [
+            {
+                "path": "0.1.200",
+            },
+            {
+                "path": "0.1.99",
+            },
+            {
+                "path": "0.1.100",
+            },
+        ]
+        assert makeas(remove_these, expected) == expected
+
+
+class TestKeepLatestNFilesInFolder:
+    def test_basic_case(self):
+        data = [
+            {
+                "path": "folder1",
+                "name": "0.0.2.zip",
+                "created": "2021-03-20T13:54:52.383+02:00",
+            },
+            {
+                "path": "folder1",
+                "name": "0.0.1.zip",
+                "created": "2021-03-19T13:53:52.383+02:00",
+            },
+            {
+                "path": "folder2",
+                "name": "0.0.1.zip",
+                "created": "2021-03-19T13:53:52.383+02:00",
+            },
+            {
+                "path": "folder2",
+                "name": "0.0.2.zip",
+                "created": "2021-03-20T13:54:52.383+02:00",
+            },
+            {
+                "path": "folder3",
+                "name": "0.0.1.zip",
+                "created": "2021-03-20T13:54:52.383+02:00",
+            },
+        ]
+
+        artifacts = ArtifactsList.from_response(data)
+
+        remove_these = KeepLatestNFilesInFolder(1).filter(artifacts)
+        expected = [
+            {"name": "0.0.1.zip", "path": "folder1"},
+            {"name": "0.0.1.zip", "path": "folder2"},
+        ]
+        assert makeas(remove_these, expected) == expected
+
+
+class TestKeepLatestVersionNFilesInFolder:
+    def test_default_regexp(self):
+        data = [
+            {
+                "path": "folder1",
+                "name": "0.0.2.zip",
+                "created": "2021-03-20T13:54:52.383+02:00",
+            },
+            {
+                "path": "folder1",
+                "name": "0.0.1.zip",
+                "created": "2021-03-19T13:53:52.383+02:00",
+            },
+            {
+                "path": "folder2",
+                "name": "0.0.1.zip",
+                "created": "2021-03-20T13:54:52.383+02:00",
+            },
+            {
+                "path": "folder2",
+                "name": "0.0.2.zip",
+                "created": "2021-03-19T13:53:52.383+02:00",
+            },
+            {
+                "path": "folder3",
+                "name": "0.0.1.zip",
+                "created": "2021-03-20T13:54:52.383+02:00",
+            },
+        ]
+
+        artifacts = ArtifactsList.from_response(data)
+
+        remove_these = KeepLatestVersionNFilesInFolder(1).filter(artifacts)
+        expected = [
+            {"name": "0.0.1.zip", "path": "folder1"},
+            {"name": "0.0.1.zip", "path": "folder2"},
+        ]
+        assert makeas(remove_these, expected) == expected
+
+    def test_custom_regexp_work(self):
+        data = [
+            {
+                "path": "folder1",
+                "name": "0.0.2.zip",
+                "created": "2021-03-20T13:54:52.383+02:00",
+            },
+            {
+                "path": "folder1",
+                "name": "0.0.1.zip",
+                "created": "2021-03-19T13:53:52.383+02:00",
+            },
+            {
+                "path": "folder2",
+                "name": "0.0.1.zip",
+                "created": "2021-03-20T13:54:52.383+02:00",
+            },
+            {
+                "path": "folder2",
+                "name": "0.0.2.zip",
+                "created": "2021-03-19T13:53:52.383+02:00",
+            },
+            {
+                "path": "folder3",
+                "name": "0.0.1.zip",
+                "created": "2021-03-20T13:54:52.383+02:00",
+            },
+            {
+                "path": "folder3",
+                "name": "1.0.1.zip",
+                "created": "2021-03-21T13:54:52.383+02:00",
+            },
+            {
+                "path": "folder3",
+                "name": "1.0.2.zip",
+                "created": "2021-03-21T14:54:52.383+02:00",
+            },
+        ]
+
+        artifacts = ArtifactsList.from_response(data)
+
+        remove_these = KeepLatestVersionNFilesInFolder(
+            1, "[\\d]+\\.([\\d]+\\.[\\d]+)"
+        ).filter(artifacts)
+        expected = [
+            {"name": "0.0.1.zip", "path": "folder1"},
+            {"name": "0.0.1.zip", "path": "folder2"},
+            {"name": "1.0.1.zip", "path": "folder3"},
+        ]
+        assert makeas(remove_these, expected) == expected
+
+    def test_regexp_fail_to_parse__must_keep_unmatched_files(self):
+        data = [
+            {
+                "path": "folder1",
+                "name": "0.0.2.zip",
+                "created": "2021-03-20T13:54:52.383+02:00",
+            },
+            {
+                "path": "folder1",
+                "name": "0.0.1.zip",
+                "created": "2021-03-19T13:53:52.383+02:00",
+            },
+            {
+                "path": "folder2",
+                "name": "0.0.1.zip",
+                "created": "2021-03-20T13:54:52.383+02:00",
+            },
+            {
+                "path": "folder2",
+                "name": "0.0.2.zip",
+                "created": "2021-03-19T13:53:52.383+02:00",
+            },
+            {
+                "path": "folder3",
+                "name": "0.0.1.zip",
+                "created": "2021-03-20T13:54:52.383+02:00",
+            },
+        ]
+
+        artifacts = ArtifactsList.from_response(data)
+
+        remove_these = KeepLatestVersionNFilesInFolder(
+            1, "[^\\d][\\._]((\\d+\\.)+\\d+)"
+        ).filter(artifacts)
+        expected = []
+        assert remove_these == expected
+
+    def test_regexp_with_hyphen(self):
+        data = [
+            # bootstrap-gui
+            {
+                "path": "folder1",
+                "name": "bootstrap-gui-3.10-39.src.rpm",
+                "created": "2021-03-20T13:54:52.383+02:00",
+            },
+            {
+                "path": "folder1",
+                "name": "bootstrap-gui-3.10-33.src.rpm",
+                "created": "2021-03-20T13:54:52.383+02:00",
+            },
+            {
+                "path": "folder1",
+                "name": "bootstrap-gui-3.11-33.src.rpm",
+                "created": "2021-03-19T13:53:52.383+02:00",
+            },
+            {
+                "path": "folder1",
+                "name": "bootstrap-gui-4.11-33.src.rpm",
+                "created": "2021-03-20T13:54:52.383+02:00",
+            },
+        ]
+
+        artifacts = ArtifactsList.from_response(data)
+
+        remove_these = KeepLatestVersionNFilesInFolder(
+            2, "bootstrap-gui-([\\d]+\\.[\\d]+\\-[\\d]+).*\\.rpm"
+        ).filter(artifacts)
+        expected = [
+            {"name": "bootstrap-gui-3.10-39.src.rpm", "path": "folder1"},
+            {"name": "bootstrap-gui-3.10-33.src.rpm", "path": "folder1"},
+        ]
+        assert makeas(remove_these, expected) == expected