diff --git a/uncertainties/test_uncertainties.py b/uncertainties/test_uncertainties.py
index c5ed4ccc..88b7a688 100644
--- a/uncertainties/test_uncertainties.py
+++ b/uncertainties/test_uncertainties.py
@@ -1704,10 +1704,10 @@ def test_format():
         (1234.56789, 0.1): {
             'eL': r'\left(1.23457 \pm 0.00010\right) \times 10^{3}',
             'EL': r'\left(1.23457 \pm 0.00010\right) \times 10^{3}',
-            'fL': '1234.57 \pm 0.10',
-            'FL': '1234.57 \pm 0.10',
-            'fL': '1234.57 \pm 0.10',
-            'FL': '1234.57 \pm 0.10',
+            'fL': r'1234.57 \pm 0.10',
+            'FL': r'1234.57 \pm 0.10',
+            'fL': r'1234.57 \pm 0.10',
+            'FL': r'1234.57 \pm 0.10',
             '%L': r'\left(123457 \pm 10\right) \%'
         },
         #
@@ -1747,7 +1747,7 @@ def test_format():
             '15GS': '  -1.2(%s)E-12' % NaN_EFG,
             'SL': r'-1.2(\mathrm{nan}) \times 10^{-12}',  # LaTeX NaN
             # Pretty-print priority, but not for NaN:
-            'PSL': u'-1.2(\mathrm{nan})×10⁻¹²',
+            'PSL': r'-1.2(\mathrm{nan})×10⁻¹²',
             'L': r'\left(-1.2 \pm \mathrm{nan}\right) \times 10^{-12}',
             # Uppercase NaN and LaTeX:
             '.1EL': (r'\left(-1.2 \pm \mathrm{%s}\right) \times 10^{-12}'
@@ -1826,8 +1826,8 @@ def test_format():
             # Default precision = 6
             'eL': r'\left(1.234568 \pm 0\right) \times 10^{3}',
             'EL': r'\left(1.234568 \pm 0\right) \times 10^{3}',
-            'fL': '1234.567890 \pm 0',
-            'FL': '1234.567890 \pm 0',
+            'fL': r'1234.567890 \pm 0',
+            'FL': r'1234.567890 \pm 0',
             '%L': r'\left(123456.789000 \pm 0\right) \%'
         },
 
@@ -1992,9 +1992,9 @@ def test_format():
         # options:
         (float('-inf'), float('inf')): {
             'S': '-inf(inf)',
-            'LS': '-\infty(\infty)',
-            'L': '-\infty \pm \infty',
-            'LP': u'-\infty±\infty',
+            'LS': r'-\infty(\infty)',
+            'L': r'-\infty \pm \infty',
+            'LP': r'-\infty±\infty',
             # The following is consistent with Python's own
             # formatting, which depends on the version of Python:
             # formatting float("-inf") with format(..., "020") gives
@@ -2018,9 +2018,9 @@ def test_format():
         },
         (-float('nan'), float('inf')): {
             'S': 'nan(inf)',
-            'LS': '\mathrm{nan}(\infty)',
-            'L': '\mathrm{nan} \pm \infty',
-            'LP': u'\mathrm{nan}±\infty'
+            'LS': r'\mathrm{nan}(\infty)',
+            'L': r'\mathrm{nan} \pm \infty',
+            'LP': r'\mathrm{nan}±\infty'
         },
 
         # Leading zeroes in the shorthand notation:
@@ -2140,7 +2140,7 @@ def test_custom_pretty_print_and_latex():
     PREV_CUSTOMIZATIONS = {
         var: getattr(uncert_core, var).copy()
         for var in ['PM_SYMBOLS', 'MULT_SYMBOLS', 'GROUP_SYMBOLS']}
-    
+
     # Customizations:
     for format in ["pretty-print", "latex"]:
         uncert_core.PM_SYMBOLS[format] = u" ± "
@@ -2196,7 +2196,7 @@ def arrays_close(m1, m2, precision=1e-4):
             if not numbers_close(elmt1.std_dev,
                                  elmt2.std_dev, precision):
                 return False
-        
+
         return True
 
 
@@ -2350,10 +2350,10 @@ def test_correlated_values():
 
         for (variable, nom_value, variance) in zip(
             variables, nom_values, cov.diagonal()):
-            
+
             assert numbers_close(variable.n, nom_value)
-            assert numbers_close(variable.s**2, variance) 
-        
+            assert numbers_close(variable.s**2, variance)
+
         assert arrays_close(
             cov,
             numpy.array(uncert_core.covariance_matrix(variables)))