diff --git a/src/multicsv/file.py b/src/multicsv/file.py
index 26ffac3..fb1ef0d 100644
--- a/src/multicsv/file.py
+++ b/src/multicsv/file.py
@@ -115,6 +115,8 @@ def __init__(self, file: TextIO):
         self._initialized = True
 
     def __getitem__(self, key: str) -> TextIO:
+        self._check_closed()
+
         for item in self._sections:
             if item.name == key:
                 return item.descriptor
@@ -123,6 +125,8 @@ def __getitem__(self, key: str) -> TextIO:
                               f"have section named {key!r}.")
 
     def __setitem__(self, key: str, value: TextIO) -> None:
+        self._check_closed()
+
         def make_section() -> MultiCSVSection:
             return MultiCSVSection(name=key, descriptor=value)
 
@@ -134,6 +138,8 @@ def make_section() -> MultiCSVSection:
         self._sections.append(make_section())
 
     def __delitem__(self, key: str) -> None:
+        self._check_closed()
+
         found = None
         for i, item in enumerate(self._sections):
             if item.name == key:
@@ -147,12 +153,16 @@ def __delitem__(self, key: str) -> None:
             del self._sections[i]
 
     def __iter__(self) -> Iterator[str]:
+        self._check_closed()
+
         return iter(map(lambda x: x.name, self._sections))
 
     def __len__(self) -> int:
         return len(self._sections)
 
     def __contains__(self, key: object) -> bool:
+        self._check_closed()
+
         for item in self._sections:
             if item.name == key:
                 return True
diff --git a/tests/test_file.py b/tests/test_file.py
index a6f15e4..330ec13 100644
--- a/tests/test_file.py
+++ b/tests/test_file.py
@@ -2,7 +2,7 @@
 import pytest
 from typing import TextIO
 from multicsv.file import MultiCSVFile
-from multicsv.exceptions import SectionNotFound, CSVFileBaseIOClosed
+from multicsv.exceptions import SectionNotFound, CSVFileBaseIOClosed, OpOnClosedCSVFileError
 
 
 @pytest.fixture
@@ -189,3 +189,26 @@ def test_various_initial_contents(initial_content, expected_sections):
     file = io.StringIO(initial_content)
     csv_file = MultiCSVFile(file)
     assert list(iter(csv_file)) == expected_sections
+
+
+def test_op_on_closed(simple_csv):
+    csv_file = MultiCSVFile(simple_csv)
+
+    assert csv_file["section1"]
+    csv_file.close()
+
+    with pytest.raises(OpOnClosedCSVFileError):
+        csv_file["section1"]
+
+    csv_file.close()
+
+    with pytest.raises(OpOnClosedCSVFileError):
+        csv_file["section1"]
+
+
+def test_op_on_closed_via_context(simple_csv):
+    with MultiCSVFile(simple_csv) as csv_file:
+        assert csv_file["section1"]
+
+    with pytest.raises(OpOnClosedCSVFileError):
+        csv_file["section1"]