diff --git a/mkl_fft/tests/test_fft1d.py b/mkl_fft/tests/test_fft1d.py
index 16464e75..6cd0e2dc 100644
--- a/mkl_fft/tests/test_fft1d.py
+++ b/mkl_fft/tests/test_fft1d.py
@@ -357,14 +357,18 @@ def test_array6(self):
 def test_fft_out_strided(axis, func):
     shape = (20, 33, 54)
     x = rnd.random(shape) + 1j * rnd.random(shape)
-    out = np.empty(shape, dtype=x.dtype)
+    base = np.full(shape, -1 - 1j)
 
     x = x[::2, ::3, ::4]
-    out = np.empty(x.shape, dtype=x.dtype)
+    out = base[::2, ::3, ::4]
     result = getattr(mkl_fft, func)(x, axis=axis, out=out)
-    expected = getattr(np.fft, func)(x, axis=axis, out=out)
+    expected = getattr(np.fft, func)(x, axis=axis)
 
+    assert result is out
     assert_allclose(result, expected)
+    # nothing outside of out was written to
+    out[...] = -1 - 1j
+    assert np.all(base == -1 - 1j)
 
 
 @requires_numpy_2
@@ -378,14 +382,18 @@ def test_rfft_out_strided(axis):
         out_sh = (20, 18, 54)
     else:  # axis == 2
         out_sh = (20, 33, 32)
-    out = np.empty(out_sh, dtype=np.complex128)
+    base = np.full(out_sh, -1 - 1j)
 
     x = x[::2, ::3, ::4]
-    out = out[::2, ::3, ::4]
+    out = base[::2, ::3, ::4]
     result = mkl_fft.rfft(x, axis=axis, out=out)
-    expected = np.fft.rfft(x, axis=axis, out=out)
+    expected = np.fft.rfft(x, axis=axis)
 
+    assert result is out
     assert_allclose(result, expected)
+    # nothing outside of out was written to
+    out[...] = -1 - 1j
+    assert np.all(base == -1 - 1j)
 
 
 @requires_numpy_2
@@ -399,14 +407,18 @@ def test_irfft_out_strided(axis):
         out_sh = (20, 60, 54)
     else:  # axis == 2
         out_sh = (20, 33, 104)
-    out = np.empty(out_sh, dtype=np.float64)
+    base = np.full(out_sh, -1.0)
 
     x = x[::2, ::3, ::4]
-    out = out[::2, ::3, ::4]
+    out = base[::2, ::3, ::4]
     result = mkl_fft.irfft(x, axis=axis, out=out)
-    expected = np.fft.irfft(x, axis=axis, out=out)
+    expected = np.fft.irfft(x, axis=axis)
 
+    assert result is out
     assert_allclose(result, expected)
+    # nothing outside of out was written to
+    out[...] = -1.0
+    assert np.all(base == -1.0)
 
 
 @requires_numpy_2
diff --git a/mkl_fft/tests/test_fftnd.py b/mkl_fft/tests/test_fftnd.py
index 4aa6f159..923f8a4c 100644
--- a/mkl_fft/tests/test_fftnd.py
+++ b/mkl_fft/tests/test_fftnd.py
@@ -299,14 +299,18 @@ def test_repeated_axes(dtype, axes, func):
 def test_out_strided(axes, func):
     shape = (20, 30, 40)
     x = rnd.random(shape) + 1j * rnd.random(shape)
-    out = np.empty(shape, dtype=x.dtype)
+    base = np.full(shape, -1 - 1j)
 
     x = x[::2, ::3, ::4]
-    out = out[::2, ::3, ::4]
+    out = base[::2, ::3, ::4]
     result = getattr(mkl_fft, func)(x, axes=axes, out=out)
-    expected = getattr(np.fft, func)(x, axes=axes, out=out)
+    expected = getattr(np.fft, func)(x, axes=axes)
 
+    assert result is out
     assert_allclose(result, expected, strict=True)
+    # nothing outside of out was written to
+    out[...] = -1 - 1j
+    assert np.all(base == -1 - 1j)
 
 
 @pytest.mark.parametrize(