diff --git a/openmc/checkvalue.py b/openmc/checkvalue.py
index 01613908b..948862399 100644
--- a/openmc/checkvalue.py
+++ b/openmc/checkvalue.py
@@ -17,15 +17,15 @@ def check_type(name, value, expected_type, expected_iter_type=None):
     """
 
     if not isinstance(value, expected_type):
-        msg = 'Unable to set {0} to {1} which is not of type {2}'.format(
+        msg = 'Unable to set "{0}" to "{1}" which is not of type "{2}"'.format(
             name, value, expected_type.__name__)
         raise ValueError(msg)
 
     if expected_iter_type:
         for item in value:
             if not isinstance(item, expected_iter_type):
-                msg = 'Unable to set {0} to {1} since each item must be ' \
-                      'of type {2}'.format(name, value,
+                msg = 'Unable to set "{0}" to "{1}" since each item must be ' \
+                      'of type "{2}"'.format(name, value,
                                            expected_iter_type.__name__)
                 raise ValueError(msg)
 
@@ -49,16 +49,16 @@ def check_length(name, value, length_min, length_max=None):
 
     if length_max is None:
         if len(value) != length_min:
-            msg = 'Unable to set {0} to {1} since it must be of ' \
-                  'length {2}'.format(name, value, length_min)
+            msg = 'Unable to set "{0}" to "{1}" since it must be of ' \
+                  'length "{2}"'.format(name, value, length_min)
             raise ValueError(msg)
     elif not length_min <= len(value) <= length_max:
         if length_min == length_max:
-            msg = 'Unable to set {0} to {1} since it must be of ' \
-                  'length {2}'.format(name, value, length_min)
+            msg = 'Unable to set "{0}" to "{1}" since it must be of ' \
+                  'length "{2}"'.format(name, value, length_min)
         else:
-            msg = 'Unable to set {0} to {1} since it must have length ' \
-                  'between {2} and {3}'.format(name, value, length_min,
+            msg = 'Unable to set "{0}" to "{1}" since it must have length ' \
+                  'between "{2}" and "{3}"'.format(name, value, length_min,
                                                length_max)
         raise ValueError(msg)
 
@@ -78,7 +78,7 @@ def check_value(name, value, accepted_values):
     """
 
     if value not in accepted_values:
-        msg = 'Unable to set {0} to {1} since it is not in {2}'.format(
+        msg = 'Unable to set "{0}" to "{1}" since it is not in "{2}"'.format(
             name, value, accepted_values)
         raise ValueError(msg)
 
@@ -100,13 +100,13 @@ def check_less_than(name, value, maximum, equality=False):
 
     if equality:
         if value > maximum:
-            msg = 'Unable to set {0} to {1} since it is greater than ' \
-                  '{2}'.format(name, value, maximum)
+            msg = 'Unable to set "{0}" to "{1}" since it is greater than ' \
+                  '"{2}"'.format(name, value, maximum)
             raise ValueError(msg)
     else:
         if value >= maximum:
-            msg = 'Unable to set {0} to {1} since it is greater than ' \
-                  'or equal to {2}'.format(name, value, maximum)
+            msg = 'Unable to set "{0}" to "{1}" since it is greater than ' \
+                  'or equal to "{2}"'.format(name, value, maximum)
             raise ValueError(msg)
 
 def check_greater_than(name, value, minimum, equality=False):
@@ -127,11 +127,11 @@ def check_greater_than(name, value, minimum, equality=False):
 
     if equality:
         if value < minimum:
-            msg = 'Unable to set {0} to {1} since it is less than ' \
-                  '{2}'.format(name, value, minimum)
+            msg = 'Unable to set "{0}" to "{1}" since it is less than ' \
+                  '"{2}"'.format(name, value, minimum)
             raise ValueError(msg)
     else:
         if value <= minimum:
-            msg = 'Unable to set {0} to {1} since it is less than ' \
-                  'or equal to {2}'.format(name, value, minimum)
+            msg = 'Unable to set "{0}" to "{1}" since it is less than ' \
+                  'or equal to "{2}"'.format(name, value, minimum)
             raise ValueError(msg)
diff --git a/openmc/executor.py b/openmc/executor.py
index 6dfb3566c..54c8a64c1 100644
--- a/openmc/executor.py
+++ b/openmc/executor.py
@@ -50,7 +50,7 @@ class Executor(object):
         check_type("Executor's working directory", working_directory,
                    basestring)
         if not os.path.isdir(working_directory):
-            msg = 'Unable to set Executor\'s working directory to {0} ' \
+            msg = 'Unable to set Executor\'s working directory to "{0}" ' \
                   'which does not exist'.format(working_directory)
             raise ValueError(msg)
 
diff --git a/openmc/filter.py b/openmc/filter.py
index b46144f6c..c9ff24803 100644
--- a/openmc/filter.py
+++ b/openmc/filter.py
@@ -136,30 +136,30 @@ class Filter(object):
                           'universe', 'distribcell']:
             for edge in bins:
                 if not isinstance(edge, Integral):
-                    msg = 'Unable to add bin "{0}" to a {1} Filter since ' \
+                    msg = 'Unable to add bin "{0}" to a "{1}" Filter since ' \
                           'it is not an integer'.format(edge, self._type)
                     raise ValueError(msg)
                 elif edge < 0:
-                    msg = 'Unable to add bin "{0}" to a {1} Filter since ' \
+                    msg = 'Unable to add bin "{0}" to a "{1}" Filter since ' \
                           'it is negative'.format(edge, self._type)
                     raise ValueError(msg)
 
         elif self._type in ['energy', 'energyout']:
             for edge in bins:
                 if not isinstance(edge, Real):
-                    msg = 'Unable to add bin edge "{0}" to a {1} Filter ' \
+                    msg = 'Unable to add bin edge "{0}" to a "{1}" Filter ' \
                           'since it is a non-integer or floating point ' \
                           'value'.format(edge, self.type)
                     raise ValueError(msg)
                 elif edge < 0.:
-                    msg = 'Unable to add bin edge "{0}" to a {1} Filter ' \
+                    msg = 'Unable to add bin edge "{0}" to a "{1}" Filter ' \
                           'since it is a negative value'.format(edge, self.type)
                     raise ValueError(msg)
 
             # Check that bin edges are monotonically increasing
             for index in range(len(bins)):
                 if index > 0 and bins[index] < bins[index-1]:
-                    msg = 'Unable to add bin edges "{0}" to a {1} Filter ' \
+                    msg = 'Unable to add bin edges "{0}" to a "{1}" Filter ' \
                           'since they are not monotonically ' \
                           'increasing'.format(bins, self.type)
                     raise ValueError(msg)
@@ -186,7 +186,7 @@ class Filter(object):
     @num_bins.setter
     def num_bins(self, num_bins):
         if not isinstance(num_bins, Integral) or num_bins < 0:
-            msg = 'Unable to set the number of bins "{0}" for a {1} Filter ' \
+            msg = 'Unable to set the number of bins "{0}" for a "{1}" Filter ' \
                   'since it is not a positive ' \
                   'integer'.format(num_bins, self.type)
             raise ValueError(msg)
@@ -210,8 +210,8 @@ class Filter(object):
     def stride(self, stride):
         check_type('filter stride', stride, Integral)
         if stride < 0:
-            msg = 'Unable to set stride "{0}" for a {1} Filter since it is a ' \
-                  'negative value'.format(stride, self.type)
+            msg = 'Unable to set stride "{0}" for a "{1}" Filter since it ' \
+                  'is a negative value'.format(stride, self.type)
             raise ValueError(msg)
 
         self._stride = stride
@@ -269,7 +269,8 @@ class Filter(object):
         """
 
         if not self.can_merge(filter):
-            msg = 'Unable to merge {0} with {1} filters'.format(self.type, filter.type)
+            msg = 'Unable to merge "{0}" with "{1}" ' \
+                  'filters'.format(self.type, filter.type)
             raise ValueError(msg)
 
         # Create deep copy of filter to return as merged filter
diff --git a/openmc/geometry.py b/openmc/geometry.py
index 2ea9705fa..18fa698b5 100644
--- a/openmc/geometry.py
+++ b/openmc/geometry.py
@@ -34,8 +34,8 @@ class Geometry(object):
     def root_universe(self, root_universe):
         check_type('root universe', root_universe, openmc.Universe)
         if root_universe._id != 0:
-            msg = 'Unable to add root Universe {0} to Geometry since ' \
-                  'it has ID={1} instead of ' \
+            msg = 'Unable to add root Universe "{0}" to Geometry since ' \
+                  'it has ID="{1}" instead of ' \
                   'ID=0'.format(root_universe, root_universe._id)
             raise ValueError(msg)
 
diff --git a/openmc/material.py b/openmc/material.py
index 62e3d16d5..e495357b5 100644
--- a/openmc/material.py
+++ b/openmc/material.py
@@ -122,7 +122,7 @@ class Material(object):
         else:
             check_type('material ID', material_id, Integral)
             if material_id in MATERIAL_IDS:
-                msg = 'Unable to set Material ID to {0} since a Material with ' \
+                msg = 'Unable to set Material ID to "{0}" since a Material with ' \
                       'this ID was already initialized'.format(material_id)
                 raise ValueError(msg)
             check_greater_than('material ID', material_id, 0)
@@ -132,7 +132,7 @@ class Material(object):
 
     @name.setter
     def name(self, name):
-        check_type('name for Material ID={0}'.format(self._id),
+        check_type('name for Material ID="{0}"'.format(self._id),
                    name, basestring)
         self._name = name
 
@@ -149,12 +149,12 @@ class Material(object):
 
         """
 
-        check_type('the density for Material ID={0}'.format(self._id),
+        check_type('the density for Material ID="{0}"'.format(self._id),
                    density, Real)
         check_value('density units', units, DENSITY_UNITS)
 
         if density == NO_DENSITY and units is not 'sum':
-            msg = 'Unable to set the density Material ID={0} ' \
+            msg = 'Unable to set the density Material ID="{0}" ' \
                   'because a density must be set when not using ' \
                   'sum unit'.format(self._id)
             raise ValueError(msg)
@@ -169,8 +169,8 @@ class Material(object):
                       'version of openmc')
 
         if not isinstance(filename, basestring) and filename is not None:
-            msg = 'Unable to add OTF material file to Material ID={0} with a ' \
-                  'non-string name {1}'.format(self._id, filename)
+            msg = 'Unable to add OTF material file to Material ID="{0}" with a ' \
+                  'non-string name "{1}"'.format(self._id, filename)
             raise ValueError(msg)
 
         self._distrib_otf_file = filename
@@ -198,18 +198,18 @@ class Material(object):
         """
 
         if not isinstance(nuclide, (openmc.Nuclide, str)):
-            msg = 'Unable to add a Nuclide to Material ID={0} with a ' \
-                  'non-Nuclide value {1}'.format(self._id, nuclide)
+            msg = 'Unable to add a Nuclide to Material ID="{0}" with a ' \
+                  'non-Nuclide value "{1}"'.format(self._id, nuclide)
             raise ValueError(msg)
 
         elif not isinstance(percent, Real):
-            msg = 'Unable to add a Nuclide to Material ID={0} with a ' \
-                  'non-floating point value {1}'.format(self._id, percent)
+            msg = 'Unable to add a Nuclide to Material ID="{0}" with a ' \
+                  'non-floating point value "{1}"'.format(self._id, percent)
             raise ValueError(msg)
 
         elif percent_type not in ['ao', 'wo', 'at/g-cm']:
-            msg = 'Unable to add a Nuclide to Material ID={0} with a ' \
-                  'percent type {1}'.format(self._id, percent_type)
+            msg = 'Unable to add a Nuclide to Material ID="{0}" with a ' \
+                  'percent type "{1}"'.format(self._id, percent_type)
             raise ValueError(msg)
 
         if isinstance(nuclide, openmc.Nuclide):
@@ -232,7 +232,7 @@ class Material(object):
         """
 
         if not isinstance(nuclide, openmc.Nuclide):
-            msg = 'Unable to remove a Nuclide {0} in Material ID={1} ' \
+            msg = 'Unable to remove a Nuclide "{0}" in Material ID="{1}" ' \
                   'since it is not a Nuclide'.format(self._id, nuclide)
             raise ValueError(msg)
 
@@ -255,18 +255,18 @@ class Material(object):
         """
 
         if not isinstance(element, openmc.Element):
-            msg = 'Unable to add an Element to Material ID={0} with a ' \
-                  'non-Element value {1}'.format(self._id, element)
+            msg = 'Unable to add an Element to Material ID="{0}" with a ' \
+                  'non-Element value "{1}"'.format(self._id, element)
             raise ValueError(msg)
 
         if not isinstance(percent, Real):
-            msg = 'Unable to add an Element to Material ID={0} with a ' \
-                  'non-floating point value {1}'.format(self._id, percent)
+            msg = 'Unable to add an Element to Material ID="{0}" with a ' \
+                  'non-floating point value "{1}"'.format(self._id, percent)
             raise ValueError(msg)
 
         if percent_type not in ['ao', 'wo']:
-            msg = 'Unable to add an Element to Material ID={0} with a ' \
-                  'percent type {1}'.format(self._id, percent_type)
+            msg = 'Unable to add an Element to Material ID="{0}" with a ' \
+                  'percent type "{1}"'.format(self._id, percent_type)
             raise ValueError(msg)
 
         # Copy this Element to separate it from same Element in other Materials
@@ -301,13 +301,13 @@ class Material(object):
         """
 
         if not isinstance(name, basestring):
-            msg = 'Unable to add an S(a,b) table to Material ID={0} with a ' \
-                        'non-string table name {1}'.format(self._id, name)
+            msg = 'Unable to add an S(a,b) table to Material ID="{0}" with a ' \
+                        'non-string table name "{1}"'.format(self._id, name)
             raise ValueError(msg)
 
         if not isinstance(xs, basestring):
-            msg = 'Unable to add an S(a,b) table to Material ID={0} with a ' \
-                  'non-string cross-section identifier {1}'.format(self._id, xs)
+            msg = 'Unable to add an S(a,b) table to Material ID="{0}" with a ' \
+                  'non-string cross-section identifier "{1}"'.format(self._id, xs)
             raise ValueError(msg)
 
         self._sab.append((name, xs))
@@ -332,7 +332,7 @@ class Material(object):
 
         return nuclides
 
-    def _repr__(self):
+    def __repr__(self):
         string = 'Material\n'
         string += '{0: <16}{1}{2}\n'.format('\tID', '=\t', self._id)
         string += '{0: <16}{1}{2}\n'.format('\tName', '=\t', self._name)
@@ -522,7 +522,7 @@ class MaterialsFile(object):
         """
 
         if not isinstance(material, Material):
-            msg = 'Unable to add a non-Material {0} to the ' \
+            msg = 'Unable to add a non-Material "{0}" to the ' \
                   'MaterialsFile'.format(material)
             raise ValueError(msg)
 
@@ -539,7 +539,7 @@ class MaterialsFile(object):
         """
 
         if not isinstance(materials, Iterable):
-            msg = 'Unable to create OpenMC materials.xml file from {0} which ' \
+            msg = 'Unable to create OpenMC materials.xml file from "{0}" which ' \
                   'is not iterable'.format(materials)
             raise ValueError(msg)
 
@@ -557,7 +557,7 @@ class MaterialsFile(object):
         """
 
         if not isinstance(material, Material):
-            msg = 'Unable to remove a non-Material {0} from the ' \
+            msg = 'Unable to remove a non-Material "{0}" from the ' \
                   'MaterialsFile'.format(material)
             raise ValueError(msg)
 
diff --git a/openmc/mesh.py b/openmc/mesh.py
index 1ba0f28a5..7e907aaa5 100644
--- a/openmc/mesh.py
+++ b/openmc/mesh.py
@@ -148,14 +148,14 @@ class Mesh(object):
 
     @name.setter
     def name(self, name):
-        check_type('name for mesh ID={0}'.format(self._id), name, basestring)
+        check_type('name for mesh ID="{0}"'.format(self._id), name, basestring)
         self._name = name
 
     @type.setter
     def type(self, meshtype):
-        check_type('type for mesh ID={0}'.format(self._id),
+        check_type('type for mesh ID="{0}"'.format(self._id),
                    meshtype, basestring)
-        check_value('type for mesh ID={0}'.format(self._id),
+        check_value('type for mesh ID="{0}"'.format(self._id),
                     meshtype, ['rectangular', 'hexagonal'])
         self._type = meshtype
 
diff --git a/openmc/opencg_compatible.py b/openmc/opencg_compatible.py
index 70e6ec306..65e980c00 100644
--- a/openmc/opencg_compatible.py
+++ b/openmc/opencg_compatible.py
@@ -78,7 +78,7 @@ def get_opencg_material(openmc_material):
     """
 
     if not isinstance(openmc_material, openmc.Material):
-        msg = 'Unable to create an OpenCG Material from {0} ' \
+        msg = 'Unable to create an OpenCG Material from "{0}" ' \
               'which is not an OpenMC Material'.format(openmc_material)
         raise ValueError(msg)
 
@@ -118,7 +118,7 @@ def get_openmc_material(opencg_material):
     """
 
     if not isinstance(opencg_material, opencg.Material):
-        msg = 'Unable to create an OpenMC Material from {0} ' \
+        msg = 'Unable to create an OpenMC Material from "{0}" ' \
               'which is not an OpenCG Material'.format(opencg_material)
         raise ValueError(msg)
 
@@ -165,7 +165,7 @@ def is_opencg_surface_compatible(opencg_surface):
 
     if not isinstance(opencg_surface, opencg.Surface):
         msg = 'Unable to check if OpenCG Surface is compatible' \
-              'since {0} is not a Surface'.format(opencg_surface)
+              'since "{0}" is not a Surface'.format(opencg_surface)
         raise ValueError(msg)
 
     if opencg_surface._type in ['x-squareprism',
@@ -191,7 +191,7 @@ def get_opencg_surface(openmc_surface):
     """
 
     if not isinstance(openmc_surface, openmc.Surface):
-        msg = 'Unable to create an OpenCG Surface from {0} ' \
+        msg = 'Unable to create an OpenCG Surface from "{0}" ' \
               'which is not an OpenMC Surface'.format(openmc_surface)
         raise ValueError(msg)
 
@@ -277,7 +277,7 @@ def get_openmc_surface(opencg_surface):
     """
 
     if not isinstance(opencg_surface, opencg.Surface):
-        msg = 'Unable to create an OpenMC Surface from {0} which ' \
+        msg = 'Unable to create an OpenMC Surface from "{0}" which ' \
               'is not an OpenCG Surface'.format(opencg_surface)
         raise ValueError(msg)
 
@@ -335,7 +335,7 @@ def get_openmc_surface(opencg_surface):
 
     else:
         msg = 'Unable to create an OpenMC Surface from an OpenCG ' \
-              'Surface of type {0} since it is not a compatible ' \
+              'Surface of type "{0}" since it is not a compatible ' \
               'Surface type in OpenMC'.format(opencg_surface._type)
         raise ValueError(msg)
 
@@ -368,7 +368,7 @@ def get_compatible_opencg_surfaces(opencg_surface):
     """
 
     if not isinstance(opencg_surface, opencg.Surface):
-        msg = 'Unable to create an OpenMC Surface from {0} which ' \
+        msg = 'Unable to create an OpenMC Surface from "{0}" which ' \
               'is not an OpenCG Surface'.format(opencg_surface)
         raise ValueError(msg)
 
@@ -421,7 +421,7 @@ def get_compatible_opencg_surfaces(opencg_surface):
 
     else:
         msg = 'Unable to create a compatible OpenMC Surface an OpenCG ' \
-              'Surface of type {0} since it already a compatible ' \
+              'Surface of type "{0}" since it already a compatible ' \
               'Surface type in OpenMC'.format(opencg_surface._type)
         raise ValueError(msg)
 
@@ -450,7 +450,7 @@ def get_opencg_cell(openmc_cell):
     """
 
     if not isinstance(openmc_cell, openmc.Cell):
-        msg = 'Unable to create an OpenCG Cell from {0} which ' \
+        msg = 'Unable to create an OpenCG Cell from "{0}" which ' \
               'is not an OpenMC Cell'.format(openmc_cell)
         raise ValueError(msg)
 
@@ -518,17 +518,17 @@ def get_compatible_opencg_cells(opencg_cell, opencg_surface, halfspace):
 
     """
     if not isinstance(opencg_cell, opencg.Cell):
-        msg = 'Unable to create compatible OpenMC Cell from {0} which ' \
+        msg = 'Unable to create compatible OpenMC Cell from "{0}" which ' \
               'is not an OpenCG Cell'.format(opencg_cell)
         raise ValueError(msg)
 
     elif not isinstance(opencg_surface, opencg.Surface):
-        msg = 'Unable to create compatible OpenMC Cell since {0} is ' \
+        msg = 'Unable to create compatible OpenMC Cell since "{0}" is ' \
               'not an OpenCG Surface'.format(opencg_surface)
         raise ValueError(msg)
 
     elif halfspace not in [-1, +1]:
-        msg = 'Unable to create compatible Cell since {0}' \
+        msg = 'Unable to create compatible Cell since "{0}"' \
               'is not a +/-1 halfspace'.format(halfspace)
         raise ValueError(msg)
 
@@ -626,7 +626,7 @@ def make_opencg_cells_compatible(opencg_universe):
     """
 
     if not isinstance(opencg_universe, opencg.Universe):
-        msg = 'Unable to make compatible OpenCG Cells for {0} which ' \
+        msg = 'Unable to make compatible OpenCG Cells for "{0}" which ' \
               'is not an OpenCG Universe'.format(opencg_universe)
         raise ValueError(msg)
 
@@ -685,7 +685,7 @@ def get_openmc_cell(opencg_cell):
     """
 
     if not isinstance(opencg_cell, opencg.Cell):
-        msg = 'Unable to create an OpenMC Cell from {0} which ' \
+        msg = 'Unable to create an OpenMC Cell from "{0}" which ' \
               'is not an OpenCG Cell'.format(opencg_cell)
         raise ValueError(msg)
 
@@ -749,7 +749,7 @@ def get_opencg_universe(openmc_universe):
     """
 
     if not isinstance(openmc_universe, openmc.Universe):
-        msg = 'Unable to create an OpenCG Universe from {0} which ' \
+        msg = 'Unable to create an OpenCG Universe from "{0}" which ' \
               'is not an OpenMC Universe'.format(openmc_universe)
         raise ValueError(msg)
 
@@ -796,7 +796,7 @@ def get_openmc_universe(opencg_universe):
     """
 
     if not isinstance(opencg_universe, opencg.Universe):
-        msg = 'Unable to create an OpenMC Universe from {0} which ' \
+        msg = 'Unable to create an OpenMC Universe from "{0}" which ' \
               'is not an OpenCG Universe'.format(opencg_universe)
         raise ValueError(msg)
 
@@ -846,7 +846,7 @@ def get_opencg_lattice(openmc_lattice):
     """
 
     if not isinstance(openmc_lattice, openmc.Lattice):
-        msg = 'Unable to create an OpenCG Lattice from {0} which ' \
+        msg = 'Unable to create an OpenCG Lattice from "{0}" which ' \
               'is not an OpenMC Lattice'.format(openmc_lattice)
         raise ValueError(msg)
 
@@ -926,7 +926,7 @@ def get_openmc_lattice(opencg_lattice):
     """
 
     if not isinstance(opencg_lattice, opencg.Lattice):
-        msg = 'Unable to create an OpenMC Lattice from {0} which ' \
+        msg = 'Unable to create an OpenMC Lattice from "{0}" which ' \
               'is not an OpenCG Lattice'.format(opencg_lattice)
         raise ValueError(msg)
 
@@ -997,7 +997,7 @@ def get_opencg_geometry(openmc_geometry):
     """
 
     if not isinstance(openmc_geometry, openmc.Geometry):
-        msg = 'Unable to get OpenCG geometry from {0} which is ' \
+        msg = 'Unable to get OpenCG geometry from "{0}" which is ' \
               'not an OpenMC Geometry object'.format(openmc_geometry)
         raise ValueError(msg)
 
@@ -1037,7 +1037,7 @@ def get_openmc_geometry(opencg_geometry):
     """
 
     if not isinstance(opencg_geometry, opencg.Geometry):
-        msg = 'Unable to get OpenMC geometry from {0} which is ' \
+        msg = 'Unable to get OpenMC geometry from "{0}" which is ' \
               'not an OpenCG Geometry object'.format(opencg_geometry)
         raise ValueError(msg)
 
diff --git a/openmc/plots.py b/openmc/plots.py
index 44dde153a..66419a6ff 100644
--- a/openmc/plots.py
+++ b/openmc/plots.py
@@ -210,18 +210,18 @@ class Plot(object):
 
         for key in col_spec:
             if key < 0:
-                msg = 'Unable to create Plot ID={0} with col_spec ID {1} ' \
+                msg = 'Unable to create Plot ID="{0}" with col_spec ID "{1}" ' \
                       'which is less than 0'.format(self._id, key)
                 raise ValueError(msg)
 
             elif not isinstance(col_spec[key], Iterable):
-                msg = 'Unable to create Plot ID={0} with col_spec RGB values' \
-                      ' {1} which is not iterable'.format(self._id, col_spec[key])
+                msg = 'Unable to create Plot ID="{0}" with col_spec RGB values' \
+                      ' "{1}" which is not iterable'.format(self._id, col_spec[key])
                 raise ValueError(msg)
 
             elif len(col_spec[key]) != 3:
-                msg = 'Unable to create Plot ID={0} with col_spec RGB ' \
-                      'values of length {1} since 3 values must be ' \
+                msg = 'Unable to create Plot ID="{0}" with col_spec RGB ' \
+                      'values of length "{1}" since 3 values must be ' \
                       'input'.format(self._id, len(col_spec[key]))
                 raise ValueError(msg)
 
@@ -332,7 +332,7 @@ class PlotsFile(object):
         """
 
         if not isinstance(plot, Plot):
-            msg = 'Unable to add a non-Plot {0} to the PlotsFile'.format(plot)
+            msg = 'Unable to add a non-Plot "{0}" to the PlotsFile'.format(plot)
             raise ValueError(msg)
 
         self._plots.append(plot)
diff --git a/openmc/settings.py b/openmc/settings.py
index 60c74ab7a..981166af5 100644
--- a/openmc/settings.py
+++ b/openmc/settings.py
@@ -426,28 +426,28 @@ class SettingsFile(object):
     @keff_trigger.setter
     def keff_trigger(self, keff_trigger):
         if not isinstance(keff_trigger, dict):
-            msg = 'Unable to set a trigger on keff from {0} which ' \
+            msg = 'Unable to set a trigger on keff from "{0}" which ' \
                   'is not a Python dictionary'.format(keff_trigger)
             raise ValueError(msg)
 
         elif 'type' not in keff_trigger:
-            msg = 'Unable to set a trigger on keff from {0} which ' \
+            msg = 'Unable to set a trigger on keff from "{0}" which ' \
                   'does not have a "type" key'.format(keff_trigger)
             raise ValueError(msg)
 
         elif keff_trigger['type'] not in ['variance', 'std_dev', 'rel_err']:
             msg = 'Unable to set a trigger on keff with ' \
-                  'type {0}'.format(keff_trigger['type'])
+                  'type "{0}"'.format(keff_trigger['type'])
             raise ValueError(msg)
 
         elif 'threshold' not in keff_trigger:
-            msg = 'Unable to set a trigger on keff from {0} which ' \
+            msg = 'Unable to set a trigger on keff from "{0}" which ' \
                   'does not have a "threshold" key'.format(keff_trigger)
             raise ValueError(msg)
 
         elif not isinstance(keff_trigger['threshold'], Real):
             msg = 'Unable to set a trigger on keff with ' \
-                  'threshold {0}'.format(keff_trigger['threshold'])
+                  'threshold "{0}"'.format(keff_trigger['threshold'])
             raise ValueError(msg)
 
         self._keff_trigger = keff_trigger
@@ -574,20 +574,20 @@ class SettingsFile(object):
     @output.setter
     def output(self, output):
         if not isinstance(output, dict):
-            msg = 'Unable to set output to {0} which is not a Python ' \
+            msg = 'Unable to set output to "{0}" which is not a Python ' \
                   'dictionary of string keys and boolean values'.format(output)
             raise ValueError(msg)
 
         for element in output:
             keys = ['summary', 'cross_sections', 'tallies', 'distribmats']
             if element not in keys:
-                msg = 'Unable to set output to {0} which is unsupported by ' \
+                msg = 'Unable to set output to "{0}" which is unsupported by ' \
                       'OpenMC'.format(element)
                 raise ValueError(msg)
 
             if not isinstance(output[element], (bool, np.bool)):
-                msg = 'Unable to set output for {0} to a non-boolean ' \
-                      'value {1}'.format(element, output[element])
+                msg = 'Unable to set output for "{0}" to a non-boolean ' \
+                      'value "{1}"'.format(element, output[element])
                 raise ValueError(msg)
 
         self._output = output
@@ -753,7 +753,7 @@ class SettingsFile(object):
     def track(self, track):
         check_type('track', track, Iterable, Integral)
         if len(track) % 3 != 0:
-            msg = 'Unable to set the track to {0} since its length is ' \
+            msg = 'Unable to set the track to "{0}" since its length is ' \
                   'not a multiple of 3'.format(track)
             raise ValueError(msg)
         for t in zip(track[::3], track[1::3], track[2::3]):
@@ -832,7 +832,7 @@ class SettingsFile(object):
             len_nodemap = np.prod(self._dd_mesh_dimension)
 
         if len(nodemap) < len_nodemap or len(nodemap) > len_nodemap:
-            msg = 'Unable to set DD nodemap with length {0} which ' \
+            msg = 'Unable to set DD nodemap with length "{0}" which ' \
                   'does not have the same dimensionality as the domain ' \
                   'mesh'.format(len(nodemap))
             raise ValueError(msg)
diff --git a/openmc/statepoint.py b/openmc/statepoint.py
index e0ef003d6..6a4713e91 100644
--- a/openmc/statepoint.py
+++ b/openmc/statepoint.py
@@ -372,7 +372,7 @@ class StatePoint(object):
                      path='{0}{1}/n_bins'.format(subbase, j))[0]
 
                 if n_bins <= 0:
-                    msg = 'Unable to create Filter {0} for Tally ID={2} ' \
+                    msg = 'Unable to create Filter "{0}" for Tally ID="{1}" ' \
                           'since no bins were specified'.format(j, tally_key)
                     raise ValueError(msg)
 
@@ -748,7 +748,7 @@ class StatePoint(object):
         """
 
         if not isinstance(summary, openmc.summary.Summary):
-            msg = 'Unable to link statepoint with {0} which ' \
+            msg = 'Unable to link statepoint with "{0}" which ' \
                   'is not a Summary object'.format(summary)
             raise ValueError(msg)
 
diff --git a/openmc/tallies.py b/openmc/tallies.py
index ff44f3135..bb9aaf06d 100644
--- a/openmc/tallies.py
+++ b/openmc/tallies.py
@@ -297,7 +297,7 @@ class Tally(object):
         """
 
         if not isinstance(trigger, Trigger):
-            msg = 'Unable to add a tally trigger for Tally ID={0} to ' \
+            msg = 'Unable to add a tally trigger for Tally ID="{0}" to ' \
                   'since "{1}" is not a Trigger'.format(self.id, trigger)
             raise ValueError(msg)
 
@@ -330,7 +330,7 @@ class Tally(object):
         """
 
         if not isinstance(filter, (Filter, CrossFilter)):
-            msg = 'Unable to add Filter "{0}" to Tally ID={1} since it is ' \
+            msg = 'Unable to add Filter "{0}" to Tally ID="{1}" since it is ' \
                   'not a Filter object'.format(filter, self.id)
             raise ValueError(msg)
 
@@ -359,7 +359,7 @@ class Tally(object):
         """
 
         if not isinstance(score, (basestring, CrossScore)):
-            msg = 'Unable to add score "{0}" to Tally ID={1} since it is ' \
+            msg = 'Unable to add score "{0}" to Tally ID="{1}" since it is ' \
                   'not a string'.format(score, self.id)
             raise ValueError(msg)
 
@@ -410,7 +410,7 @@ class Tally(object):
         """
 
         if score not in self.scores:
-            msg = 'Unable to remove score "{0}" from Tally ID={1} since the ' \
+            msg = 'Unable to remove score "{0}" from Tally ID="{1}" since the ' \
                   'Tally does not contain this score'.format(score, self.id)
             ValueError(msg)
 
@@ -427,7 +427,7 @@ class Tally(object):
         """
 
         if filter not in self.filters:
-            msg = 'Unable to remove filter "{0}" from Tally ID={1} since the ' \
+            msg = 'Unable to remove filter "{0}" from Tally ID="{1}" since the ' \
                   'Tally does not contain this filter'.format(filter, self.id)
             ValueError(msg)
 
@@ -444,7 +444,7 @@ class Tally(object):
         """
 
         if nuclide not in self.nuclides:
-            msg = 'Unable to remove nuclide "{0}" from Tally ID={1} since the ' \
+            msg = 'Unable to remove nuclide "{0}" from Tally ID="{1}" since the ' \
                   'Tally does not contain this nuclide'.format(nuclide, self.id)
             ValueError(msg)
 
@@ -561,7 +561,7 @@ class Tally(object):
         """
 
         if not self.can_merge(tally):
-            msg = 'Unable to merge tally ID={0} with {1}'.format(tally.id, self.id)
+            msg = 'Unable to merge tally ID="{0}" with "{1}"'.format(tally.id, self.id)
             raise ValueError(msg)
 
         # Create deep copy of tally to return as merged tally
@@ -633,7 +633,7 @@ class Tally(object):
 
         # Scores
         if len(self.scores) == 0:
-            msg = 'Unable to get XML for Tally ID={0} since it does not ' \
+            msg = 'Unable to get XML for Tally ID="{0}" since it does not ' \
                   'contain any scores'.format(self.id)
             raise ValueError(msg)
 
@@ -688,7 +688,7 @@ class Tally(object):
         # If we did not find the Filter, throw an Exception
         if filter is None:
             msg = 'Unable to find filter type "{0}" in ' \
-                  'Tally ID={1}'.format(filter_type, self.id)
+                  'Tally ID="{1}"'.format(filter_type, self.id)
             raise ValueError(msg)
 
         return filter
@@ -859,7 +859,7 @@ class Tally(object):
            (value == 'rel_err' and self.mean is None) or \
            (value == 'sum' and self.sum is None) or \
            (value == 'sum_sq' and self.sum_sq is None):
-            msg = 'The Tally ID={0} has no data to return. Call the ' \
+            msg = 'The Tally ID="{0}" has no data to return. Call the ' \
                   'StatePoint.read_results() method before using ' \
                   'Tally.get_values(...)'.format(self.id)
             raise ValueError(msg)
@@ -959,7 +959,7 @@ class Tally(object):
         elif value == 'sum_sq':
             data = self.sum_sq[indices]
         else:
-            msg = 'Unable to return results from Tally ID={0} since the ' \
+            msg = 'Unable to return results from Tally ID="{0}" since the ' \
                   'the requested value "{1}" is not \'mean\', \'std_dev\', ' \
                   '\rel_err\', \'sum\', or \'sum_sq\''.format(self.id, value)
             raise LookupError(msg)
@@ -1010,7 +1010,7 @@ class Tally(object):
         """
 
         # Ensure that StatePoint.read_results() was called first
-        if self.mean is None or self.std_dev is None:
+        if self._sum is None or self._sum_sq is None:
             msg = 'The Tally ID={0} has no data to return. Call the ' \
                   'StatePoint.read_results() method before using ' \
                   'Tally.get_pandas_dataframe(...)'.format(self.id)
@@ -1018,7 +1018,7 @@ class Tally(object):
 
         # If using Summary, ensure StatePoint.link_with_summary(...) was called
         if summary and not self.with_summary:
-            msg = 'The Tally ID={0} has not been linked with the Summary. ' \
+            msg = 'The Tally ID="{0}" has not been linked with the Summary. ' \
                   'Call the StatePoint.link_with_summary(...) method ' \
                   'before using Tally.get_pandas_dataframe(...) with ' \
                   'Summary info'.format(self.id)
@@ -1314,30 +1314,30 @@ class Tally(object):
 
         # Ensure that StatePoint.read_results() was called first
         if self._sum is None or self._sum_sq is None:
-            msg = 'The Tally ID={0} has no data to export. Call the ' \
-                  'StatePoint.read_results() method before using ' \
+            msg = 'The Tally ID="{0}" has no data to export. Call the ' \
+                  'StatePoint.read_results() routine before using ' \
                   'Tally.export_results(...)'.format(self.id)
             raise KeyError(msg)
 
         if not isinstance(filename, basestring):
-            msg = 'Unable to export the results for Tally ID={0} to ' \
+            msg = 'Unable to export the results for Tally ID="{0}" to ' \
                   'filename="{1}" since it is not a ' \
                   'string'.format(self.id, filename)
             raise ValueError(msg)
 
         elif not isinstance(directory, basestring):
-            msg = 'Unable to export the results for Tally ID={0} to ' \
+            msg = 'Unable to export the results for Tally ID="{0}" to ' \
                   'directory="{1}" since it is not a ' \
                   'string'.format(self.id, directory)
             raise ValueError(msg)
 
         elif format not in ['hdf5', 'pkl', 'csv']:
-            msg = 'Unable to export the results for Tally ID={0} to format ' \
+            msg = 'Unable to export the results for Tally ID="{0}" to format ' \
                   '"{1}" since it is not supported'.format(self.id, format)
             raise ValueError(msg)
 
         elif not isinstance(append, bool):
-            msg = 'Unable to export the results for Tally ID={0} since the ' \
+            msg = 'Unable to export the results for Tally ID="{0}" since the ' \
                   'append parameter is not True/False'.format(self.id, append)
             raise ValueError(msg)
 
@@ -2218,7 +2218,7 @@ class TalliesFile(object):
         """
 
         if not isinstance(tally, Tally):
-            msg = 'Unable to add a non-Tally {0} to the TalliesFile'.format(tally)
+            msg = 'Unable to add a non-Tally "{0}" to the TalliesFile'.format(tally)
             raise ValueError(msg)
 
         if merge:
@@ -2289,7 +2289,7 @@ class TalliesFile(object):
         """
 
         if not isinstance(mesh, Mesh):
-            msg = 'Unable to add a non-Mesh {0} to the TalliesFile'.format(mesh)
+            msg = 'Unable to add a non-Mesh "{0}" to the TalliesFile'.format(mesh)
             raise ValueError(msg)
 
         self._meshes.append(mesh)
@@ -2333,4 +2333,4 @@ class TalliesFile(object):
         # Write the XML Tree to the tallies.xml file
         tree = ET.ElementTree(self._tallies_file)
         tree.write("tallies.xml", xml_declaration=True,
-                             encoding='utf-8', method="xml")
\ No newline at end of file
+                             encoding='utf-8', method="xml")
diff --git a/openmc/universe.py b/openmc/universe.py
index 84ce3696e..1a45d8666 100644
--- a/openmc/universe.py
+++ b/openmc/universe.py
@@ -126,8 +126,8 @@ class Cell(object):
             if fill.strip().lower() == 'void':
                 self._type = 'void'
             else:
-                msg = 'Unable to set Cell ID={0} to use a non-Material or ' \
-                       'Universe fill {1}'.format(self._id, fill)
+                msg = 'Unable to set Cell ID="{0}" to use a non-Material or ' \
+                       'Universe fill "{1}"'.format(self._id, fill)
                 raise ValueError(msg)
 
         elif isinstance(fill, openmc.Material):
@@ -140,8 +140,8 @@ class Cell(object):
             self._type = 'lattice'
 
         else:
-            msg = 'Unable to set Cell ID={0} to use a non-Material or ' \
-                   'Universe fill {1}'.format(self._id, fill)
+            msg = 'Unable to set Cell ID="{0}" to use a non-Material or ' \
+                   'Universe fill "{1}"'.format(self._id, fill)
             raise ValueError(msg)
 
         self._fill = fill
@@ -177,13 +177,13 @@ class Cell(object):
         """
 
         if not isinstance(surface, openmc.Surface):
-            msg = 'Unable to add Surface {0} to Cell ID={1} since it is ' \
+            msg = 'Unable to add Surface "{0}" to Cell ID="{1}" since it is ' \
                         'not a Surface object'.format(surface, self._id)
             raise ValueError(msg)
 
         if halfspace not in [-1, +1]:
-            msg = 'Unable to add Surface {0} to Cell ID={1} with halfspace ' \
-                  '{2} since it is not +/-1'.format(surface, self._id, halfspace)
+            msg = 'Unable to add Surface "{0}" to Cell ID="{1}" with halfspace ' \
+                  '"{2}" since it is not +/-1'.format(surface, self._id, halfspace)
             raise ValueError(msg)
 
         # If the Cell does not already contain the Surface, add it
@@ -201,7 +201,7 @@ class Cell(object):
         """
 
         if not isinstance(surface, openmc.Surface):
-            msg = 'Unable to remove Surface {0} from Cell ID={1} since it is ' \
+            msg = 'Unable to remove Surface "{0}" from Cell ID="{1}" since it is ' \
                         'not a Surface object'.format(surface, self._id)
             raise ValueError(msg)
 
@@ -452,7 +452,7 @@ class Universe(object):
         """
 
         if not isinstance(cell, Cell):
-            msg = 'Unable to add a Cell to Universe ID={0} since {1} is not ' \
+            msg = 'Unable to add a Cell to Universe ID="{0}" since "{1}" is not ' \
                   'a Cell'.format(self._id, cell)
             raise ValueError(msg)
 
@@ -472,7 +472,7 @@ class Universe(object):
         """
 
         if not isinstance(cells, Iterable):
-            msg = 'Unable to add Cells to Universe ID={0} since {1} is not ' \
+            msg = 'Unable to add Cells to Universe ID="{0}" since "{1}" is not ' \
                   'iterable'.format(self._id, cells)
             raise ValueError(msg)
 
@@ -490,7 +490,7 @@ class Universe(object):
         """
 
         if not isinstance(cell, Cell):
-            msg = 'Unable to remove a Cell from Universe ID={0} since {1} is ' \
+            msg = 'Unable to remove a Cell from Universe ID="{0}" since "{1}" is ' \
                   'not a Cell'.format(self._id, cell)
             raise ValueError(msg)