diff --git a/pandas/tests/copy_view/test_interp_fillna.py b/pandas/tests/copy_view/test_interp_fillna.py
index 5d4fd75df830c..624e841baae42 100644
--- a/pandas/tests/copy_view/test_interp_fillna.py
+++ b/pandas/tests/copy_view/test_interp_fillna.py
@@ -248,10 +248,7 @@ def test_fillna_inplace_reference(using_copy_on_write):
 
 
 def test_fillna_interval_inplace_reference(using_copy_on_write):
-    # Set dtype explicitly to avoid implicit cast when setting nan
-    ser = Series(
-        interval_range(start=0, end=5), name="a", dtype="interval[float64, right]"
-    )
+    ser = Series(interval_range(start=0, end=5), name="a")
     ser.iloc[1] = np.nan
 
     ser_orig = ser.copy()
@@ -341,4 +338,4 @@ def test_fillna_inplace_ea_noop_shares_memory(
     else:
         assert not np.shares_memory(get_array(df, "b"), get_array(view, "b"))
     df.iloc[0, 1] = 100
-    tm.assert_frame_equal(df_orig, view)
+    tm.assert_frame_equal(df_orig, view)
\ No newline at end of file