diff --git a/.coveragerc b/.coveragerc
new file mode 100644
index 0000000..67662f5
--- /dev/null
+++ b/.coveragerc
@@ -0,0 +1,3 @@
+[run]
+
+omit = tests/*
diff --git a/.gitignore b/.gitignore
index b830d6f..4688cab 100644
--- a/.gitignore
+++ b/.gitignore
@@ -5,4 +5,5 @@ __pycache__
 /build
 *.swp
 tests/*-out-*
-/.venv
\ No newline at end of file
+/.venv
+/.coverage
\ No newline at end of file
diff --git a/README.rst b/README.rst
index c640c8d..6eeb423 100644
--- a/README.rst
+++ b/README.rst
@@ -15,3 +15,5 @@
 Galaxy Image Analysis: https://github.com/BMCV/galaxy-image-analysis
 
 Use ``python -m unittest`` in the root directory of the repository to run the test suite.
+
+Use ``coverage run -m unittest && coverage html`` to generate a coverage report.
diff --git a/giatools/io.py b/giatools/io.py
index caab622..4af40fa 100644
--- a/giatools/io.py
+++ b/giatools/io.py
@@ -25,7 +25,7 @@ def imread(*args, **kwargs):
     tool has failed: https://docs.galaxyproject.org/en/latest/dev/schema.html#error-detection To prevent this, this
     wrapper around ``skimage.io.imread`` will mute all non-fatal errors.
 
-    Image loading is first attempted using ``tifffile`` (if available, more reliable for loading TIFF files), and if
+    Image loading is first attempted using `tifffile` (if available, more reliable for loading TIFF files), and if
     that fails (e.g., because the file is not a TIFF file), falls back to ``skimage.io.imread``.
     """
 
diff --git a/tests/data/input4.png b/tests/data/input4.png
new file mode 100644
index 0000000..5b7b472
Binary files /dev/null and b/tests/data/input4.png differ
diff --git a/tests/test_io.py b/tests/test_io.py
index 56a208d..f5faebd 100644
--- a/tests/test_io.py
+++ b/tests/test_io.py
@@ -1,8 +1,13 @@
 import unittest
+import unittest.mock
 
 import giatools.io
 
 
+# This tests require that the `tifffile` package is installed.
+assert giatools.io.tifffile is not None
+
+
 class imread(unittest.TestCase):
 
     def test_input1(self):
@@ -16,10 +21,28 @@ def test_input2(self):
     def test_input3(self):
         """
         This is a multi-page TIFF, that sometimes fails to load properly with ``skimage.io.imread``, but works with
-        ``tifffile``.
+        `tifffile`.
 
         For details see: https://github.com/BMCV/galaxy-image-analysis/pull/132#issuecomment-2371561435
         """
         img = giatools.io.imread('tests/data/input3.tif')
         self.assertEqual(img.shape, (5, 198, 356))
         self.assertEqual(img.mean(), 1259.6755334241288)
+
+    def test_input4(self):
+        """
+        This is an RGB PNG file, that cannot be loaded with `tifffile`, but works with ``skimage.io.imread``.
+        """
+        img = giatools.io.imread('tests/data/input4.png')
+        self.assertEqual(img.shape, (10, 10, 3))
+        self.assertEqual(img.mean(), 130.04)
+
+    @unittest.mock.patch('skimage.io.imread')
+    @unittest.mock.patch('giatools.io.tifffile', None)
+    def test_without_tifffile(self, mock_skimage_io_imread):
+        """
+        Test that loading an image without `tifffile` installed falls back to ``skimage.io.imread``.
+        """
+        img = giatools.io.imread('tests/data/input1.tif')
+        mock_skimage_io_imread.assert_called_once_with('tests/data/input1.tif')
+        self.assertIs(img, mock_skimage_io_imread.return_value)