diff --git a/.github/workflows/.tests-python.yml b/.github/workflows/.tests-python.yml
new file mode 100644
index 0000000..91f551a
--- /dev/null
+++ b/.github/workflows/.tests-python.yml
@@ -0,0 +1,26 @@
+name: Unit tests
+
+on:
+  push:
+  pull_request:
+
+jobs:
+  tests:
+    name: python ${{ matrix.python-version }}
+    runs-on: ubuntu-latest
+    container: python:${{ matrix.python-version }}
+    strategy:
+      matrix:
+        python-version:  [ "3.9", "3.10", "3.11", "3.12", "3.13" ]
+    steps:
+      - uses: actions/checkout@v3
+      - name: Upgrade pip
+        run: python3 -m pip install --upgrade pip
+      - name: Create and source virtual environment
+        run: |
+          python3 -m venv .venv 
+          . .venv/bin/activate
+      - name: Install requirements
+        run: python3 -m pip install -r requirements.txt
+      - name: Run unit tests
+        run: python -m unittest
diff --git a/staticmap/tests.py b/staticmap/tests.py
index 70904ee..c9771af 100644
--- a/staticmap/tests.py
+++ b/staticmap/tests.py
@@ -1,19 +1,19 @@
 from unittest import TestCase
 
-from staticmap import StaticMap
+from staticmap.staticmap import _lat_to_y, _lon_to_x, _y_to_lat, _x_to_lon
 
 
 class LonLatConversionTest(TestCase):
     def testLon(self):
         for lon in range(-180, 180, 20):
             for zoom in range(0, 10):
-                x = _lon_to_x(zoom)
-                l = _x_to_lon(zoom)
+                x = _lon_to_x(lon, zoom)
+                l = _x_to_lon(x, zoom)
                 self.assertAlmostEqual(lon, l, places=5)
 
     def testLat(self):
         for lat in range(-89, 89, 2):
             for zoom in range(0, 10):
-                y = _lat_to_y(zoom)
-                l = _y_to_lat(zoom)
+                y = _lat_to_y(lat, zoom)
+                l = _y_to_lat(y, zoom)
                 self.assertAlmostEqual(lat, l, places=5)