diff --git a/pandas/conftest.py b/pandas/conftest.py
index 70be6b5d9fcbc..0adbaf6a112cf 100644
--- a/pandas/conftest.py
+++ b/pandas/conftest.py
@@ -256,7 +256,9 @@ def nselect_method(request):
 # ----------------------------------------------------------------
 # Missing values & co.
 # ----------------------------------------------------------------
-@pytest.fixture(params=[None, np.nan, pd.NaT, float("nan"), np.float("NaN"), pd.NA])
+@pytest.fixture(
+    params=[None, np.nan, pd.NaT, float("nan"), np.float("NaN"), pd.NA], ids=str
+)
 def nulls_fixture(request):
     """
     Fixture for each null type in pandas.
diff --git a/pandas/tests/frame/methods/test_drop_duplicates.py b/pandas/tests/frame/methods/test_drop_duplicates.py
index fd4bae26ade57..7c6391140e2bb 100644
--- a/pandas/tests/frame/methods/test_drop_duplicates.py
+++ b/pandas/tests/frame/methods/test_drop_duplicates.py
@@ -418,3 +418,10 @@ def test_drop_duplicates_ignore_index(
 
     tm.assert_frame_equal(result_df, expected)
     tm.assert_frame_equal(df, DataFrame(origin_dict))
+
+
+def test_drop_duplicates_null_in_object_column(nulls_fixture):
+    # https://github.com/pandas-dev/pandas/issues/32992
+    df = DataFrame([[1, nulls_fixture], [2, "a"]], dtype=object)
+    result = df.drop_duplicates()
+    tm.assert_frame_equal(result, df)