diff --git a/docs/supported_formats/index.rst b/docs/supported_formats/index.rst
index 2b6b42da2..8d950df91 100644
--- a/docs/supported_formats/index.rst
+++ b/docs/supported_formats/index.rst
@@ -24,6 +24,7 @@ big datasets is supported.
    edax
    emd
    empad
+   hamamatsu
    hspy
    image
    jeol
diff --git a/rsciio/tests/test_hamamatsu.py b/rsciio/tests/test_hamamatsu.py
index 7e1ab958f..2272f7636 100644
--- a/rsciio/tests/test_hamamatsu.py
+++ b/rsciio/tests/test_hamamatsu.py
@@ -69,8 +69,11 @@ def test_axes_deflection(self):
         np.testing.assert_allclose(ax1.axis[:5], expected_data_start_Y)
 
     def test_original_metadata_no_comment(self):
-        original_metadata = deepcopy(self.s.original_metadata.as_dictionary())
-        del original_metadata["Comment"]
+        original_metadata_no_comment = {
+            k: v
+            for (k, v) in self.s.original_metadata.as_dictionary().items()
+            if k != "Comment"
+        }
         expected_metadata = {
             "character_im": "IM",
             "offset_x": 0,
@@ -86,7 +89,7 @@ def test_original_metadata_no_comment(self):
             "image_height_lines": 512,
             "comment_length": 3311,
         }
-        assert expected_metadata == original_metadata
+        assert expected_metadata == original_metadata_no_comment
 
     def test_original_metadata_comment(self):
         original_metadata = self.s.original_metadata.Comment.as_dictionary()