diff --git a/.gitignore b/.gitignore
index 2843094..10f9ffd 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,8 +1,10 @@
-**/__pycache__
-
-.venv/
-dist/
+__pycache__
 
+.mypy_cache
+.pytest_cache
+.venv
 .vscode
-.python-version
+
+dist
+
 poetry.lock
diff --git a/README.md b/README.md
index b27a301..4d65f3d 100644
--- a/README.md
+++ b/README.md
@@ -25,6 +25,9 @@ Python 3.4+.
 
 ## Changelog
 
+- color-hash 1.0.4 *(2021-11-30)*
+  - Support only for python 3.6+
+  - Add tests
 - color-hash 1.0.3 *(2020-12-04)*
   - Drop support for python 2
   - Handover of project maintenance
diff --git a/colorhash/__init__.py b/colorhash/__init__.py
index fd67c3f..2128878 100644
--- a/colorhash/__init__.py
+++ b/colorhash/__init__.py
@@ -1,3 +1,3 @@
-from .colorhash import ColorHash
+from colorhash.colorhash import ColorHash
 
-__all__ = [ColorHash]
+__all__ = ["ColorHash"]
diff --git a/colorhash/colorhash.py b/colorhash/colorhash.py
index c5b391a..04e4379 100644
--- a/colorhash/colorhash.py
+++ b/colorhash/colorhash.py
@@ -16,13 +16,15 @@
 >>> c.hex
 '#2dd24b'
 """
-
 from binascii import crc32
 from numbers import Number
+from typing import Any
+from typing import Tuple
 
 
-def crc32_hash(obj):
-    """Generate a hash for ``obj``.
+def crc32_hash(obj: Any):
+    """
+    Generate a hash for ``obj``.
 
     This function first converts the object to a string and encodes it into
     UTF-8, then calculates and returns the CRC-32 checksum of the result. The
@@ -33,8 +35,9 @@ def crc32_hash(obj):
     return crc32(bs) & 0xFFFFFFFF
 
 
-def hsl2rgb(hsl):
-    """Convert an HSL color value into RGB.
+def hsl2rgb(hsl: Tuple[int, float, float]):
+    """
+    Convert an HSL color value into RGB.
 
     >>> hsl2rgb((0, 1, 0.5))
     (255, 0, 0)
@@ -70,8 +73,9 @@ def hsl2rgb(hsl):
     return tuple(rgb)
 
 
-def rgb2hex(rgb):
-    """Format an RGB color value into a hexadecimal color string.
+def rgb2hex(rgb: Tuple[int, int, int]):
+    """
+    Format an RGB color value into a hexadecimal color string.
 
     >>> rgb2hex((255, 0, 0))
     '#ff0000'
@@ -83,14 +87,15 @@ def rgb2hex(rgb):
 
 
 def color_hash(
-    obj,
+    obj: Any,
     hashfunc=crc32_hash,
     lightness=(0.35, 0.5, 0.65),
     saturation=(0.35, 0.5, 0.65),
     min_h=None,
     max_h=None,
 ):
-    """Calculate the color for the given object.
+    """
+    Calculate the color for the given object.
 
     Args:
         obj: the value.
@@ -131,7 +136,8 @@ def color_hash(
 
 
 class ColorHash:
-    """Generate a color value and provide it in several format.
+    """
+    Generate a color value and provide it in several format.
 
     This class takes the same arguments as the ``color_hash`` function.
 
diff --git a/pyproject.toml b/pyproject.toml
index 7477506..14d215b 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -1,12 +1,15 @@
 [tool.poetry]
 name = "colorhash"
-version = "1.0.3"
+version = "1.0.4"
 description = "Generate color based on any object"
 authors = [
     "dimostenis",
     "Felix Krull <f_krull@gmx.de>"
     ]
 license = "MIT"
+include = [
+    "README.md",
+    ]
 
 readme = "README.md"
 homepage = "https://github.com/dimostenis/color-hash-python"
@@ -18,16 +21,22 @@ keywords = ["color", "hash"]
 "Bug Tracker" = "https://github.com/dimostenis/color-hash-python/issues"
 
 [tool.poetry.dependencies]
-python = "^3.3"
+python = "^3.6"
 
 [tool.poetry.dev-dependencies]
 mypy = "^0.782"
 flake8 = "^3.8.3"
 black = "^20.8b1"
+pytest = "^6.2.5"
 
-[build-system]
-requires = ["poetry>=0.12"]
-build-backend = "poetry.masonry.api"
+[tool.isort]
+profile = "black"
+multi_line_output = 7
+force_single_line = true
 
 [tool.black]
 line-length = 88
+
+[build-system]
+requires = ["poetry>=0.12"]
+build-backend = "poetry.masonry.api"
diff --git a/test/test_colorhash.py b/test/test_colorhash.py
new file mode 100644
index 0000000..1e8c325
--- /dev/null
+++ b/test/test_colorhash.py
@@ -0,0 +1,28 @@
+from pytest import fixture
+
+from colorhash import ColorHash
+
+
+@fixture
+def objs():
+    return (
+        "foo",
+        "bar",
+        None,
+        [0, 1],
+        {1, 2},
+        {"a": 0},
+        ColorHash("w00t"),
+    )
+
+
+def test_colorhash_returns_some_color(objs):
+
+    for obj in objs:
+        assert isinstance(ColorHash(obj).hex, str)
+
+
+def test_colorhash_is_deterministic(objs):
+
+    for obj in objs:
+        assert ColorHash(obj).hex == ColorHash(obj).hex