diff --git a/madarrays/tests/test_madarray.py b/madarrays/tests/test_madarray.py
index 29ad6412490b69ea05e1d30f9054e6e502ef7356..028ff949bae78a2c305c355127d3dc816aba75b8 100644
--- a/madarrays/tests/test_madarray.py
+++ b/madarrays/tests/test_madarray.py
@@ -664,6 +664,7 @@ class TestMadArray:
 
     def test_str_repr(self):
 
+        # test when no data is missing
         x = np.copy(self.x_float)
         arr_str = np.ndarray.__str__(x)
 
@@ -671,9 +672,10 @@ class TestMadArray:
         string = 'MadArray, dtype=float64, 0 missing entries (0.0%)\n{}'
         assert str(ma) == string.format(arr_str)
 
+        # test with missing data, float values
         x[self.m] = np.nan
         arr_str = np.ndarray.__str__(x)
-        arr_str = arr_str.replace('nan', 'x')
+        arr_str = arr_str.replace('nan', '  x')
 
         ma = MadArray(self.x_float, self.m)
         n_miss = np.count_nonzero(self.m)
@@ -683,10 +685,11 @@ class TestMadArray:
         string = '<MadArray at {}>'
         assert repr(ma) == string.format(hex(id(ma)))
 
+        # test with missing data, float values from int
         x = np.copy(self.x_int).astype(np.float64)
         x[self.m] = np.nan
         arr_str = np.ndarray.__str__(x)
-        arr_str = arr_str.replace('nan', 'x')
+        arr_str = arr_str.replace('nan', '  x')
         arr_str = arr_str.replace('.', '')
 
         ma = MadArray(self.x_int, self.m)
diff --git a/madarrays/tests/test_waveform.py b/madarrays/tests/test_waveform.py
index 2e0fb8387f8b9ee3bd8b359dbafa7dde711de373..ffc2bcc65f25188b64871c618bea10573d4276f2 100644
--- a/madarrays/tests/test_waveform.py
+++ b/madarrays/tests/test_waveform.py
@@ -791,7 +791,7 @@ class TestWaveform:
         x = np.copy(self.x_mono)
         x[self.m_mono] = np.nan
         arr_str = np.ndarray.__str__(x)
-        arr_str = arr_str.replace('nan', 'x')
+        arr_str = arr_str.replace('nan', '  x')
         n_miss = np.count_nonzero(self.m_mono)
 
         exp_str = 'Waveform, fs={}Hz, length={}, dtype={}, {} missing '\