diff --git a/pints/_abc/__init__.py b/pints/_abc/__init__.py
index 9982bcdec..580589744 100644
--- a/pints/_abc/__init__.py
+++ b/pints/_abc/__init__.py
@@ -37,7 +37,7 @@ def tell(self, x):
         raise NotImplementedError
 
 
-class ABCController(object):
+class ABCController():
     """
     Samples from a :class:`pints.LogPrior`.
 
diff --git a/pints/_boundaries.py b/pints/_boundaries.py
index d5c8c18d0..0e8b82c0c 100644
--- a/pints/_boundaries.py
+++ b/pints/_boundaries.py
@@ -9,7 +9,7 @@
 import numpy as np
 
 
-class Boundaries(object):
+class Boundaries():
     """
     Abstract class representing boundaries on a parameter space.
     """
diff --git a/pints/_core.py b/pints/_core.py
index 620fbf279..86f966a2e 100644
--- a/pints/_core.py
+++ b/pints/_core.py
@@ -9,7 +9,7 @@
 import pints
 
 
-class ForwardModel(object):
+class ForwardModel():
 
     """
     Defines an interface for user-supplied forward models.
@@ -99,7 +99,7 @@ def simulateS1(self, parameters, times):
         raise NotImplementedError
 
 
-class SingleOutputProblem(object):
+class SingleOutputProblem():
 
     """
     Represents an inference problem where a model is fit to a single time
@@ -210,7 +210,7 @@ def values(self):
         return self._values
 
 
-class MultiOutputProblem(object):
+class MultiOutputProblem():
 
     """
     Represents an inference problem where a model is fit to a multi-valued time
@@ -327,7 +327,7 @@ def values(self):
         return self._values
 
 
-class TunableMethod(object):
+class TunableMethod():
 
     """
     Defines an interface for a numerical method with a given number of
diff --git a/pints/_error_measures.py b/pints/_error_measures.py
index 0017d075b..8d691906f 100644
--- a/pints/_error_measures.py
+++ b/pints/_error_measures.py
@@ -9,7 +9,7 @@
 import numpy as np
 
 
-class ErrorMeasure(object):
+class ErrorMeasure():
     """
     Abstract base class for objects that calculate some scalar measure of
     goodness-of-fit (for a model and a data set), such that a smaller value
diff --git a/pints/_evaluation.py b/pints/_evaluation.py
index 26c991363..81b4fea77 100644
--- a/pints/_evaluation.py
+++ b/pints/_evaluation.py
@@ -60,7 +60,7 @@ def evaluate(f, x, parallel=False, args=None):
     return evaluator.evaluate(x)
 
 
-class Evaluator(object):
+class Evaluator():
     """
     Abstract base class for classes that take a function (or callable object)
     ``f(x)`` and evaluate it for list of input values ``x``.
diff --git a/pints/_log_pdfs.py b/pints/_log_pdfs.py
index 6139368f3..590bb095b 100644
--- a/pints/_log_pdfs.py
+++ b/pints/_log_pdfs.py
@@ -8,7 +8,7 @@
 import numpy as np
 
 
-class LogPDF(object):
+class LogPDF():
     """
     Represents the natural logarithm of a (not necessarily normalised)
     probability density function (PDF).
diff --git a/pints/_logger.py b/pints/_logger.py
index 709213c23..22900a18e 100644
--- a/pints/_logger.py
+++ b/pints/_logger.py
@@ -17,7 +17,7 @@
 _TEXT = 4
 
 
-class Logger(object):
+class Logger():
     """
     Logs numbers to screen and/or a file.
 
@@ -467,7 +467,7 @@ def _format_time(self, seconds):
         return '{:>3d}:{:0>4.1f}'.format(minutes, seconds)
 
 
-class Loggable(object):
+class Loggable():
     """
     Interface for classes that can log to a :class:`Logger`.
     """
diff --git a/pints/_mcmc/__init__.py b/pints/_mcmc/__init__.py
index 24913e091..287175dd7 100644
--- a/pints/_mcmc/__init__.py
+++ b/pints/_mcmc/__init__.py
@@ -239,7 +239,7 @@ def tell(self, fxs):
         raise NotImplementedError
 
 
-class MCMCController(object):
+class MCMCController():
     """
     Samples from a :class:`pints.LogPDF` using a Markov Chain Monte Carlo
     (MCMC) method.
diff --git a/pints/_mcmc/_dual_averaging.py b/pints/_mcmc/_dual_averaging.py
index 979682c17..f220d8b33 100644
--- a/pints/_mcmc/_dual_averaging.py
+++ b/pints/_mcmc/_dual_averaging.py
@@ -9,7 +9,7 @@
 import numpy as np
 
 
-class DualAveragingAdaption(object):
+class DualAveragingAdaption():
     r"""
     Dual Averaging method to adaptively tune the step size and mass matrix of a
     Hamiltonian Monte Carlo (HMC) routine (as used e.g. in NUTS).
diff --git a/pints/_mcmc/_nuts.py b/pints/_mcmc/_nuts.py
index a1fb3c9c8..ec028b4c5 100644
--- a/pints/_mcmc/_nuts.py
+++ b/pints/_mcmc/_nuts.py
@@ -11,7 +11,7 @@
 import numpy as np
 
 
-class NutsState(object):
+class NutsState():
     """
     Class to hold information about the current state of the NUTS hamiltonian
     integration path.
diff --git a/pints/_mcmc/_summary.py b/pints/_mcmc/_summary.py
index 4970cdd57..5787cc742 100644
--- a/pints/_mcmc/_summary.py
+++ b/pints/_mcmc/_summary.py
@@ -13,7 +13,7 @@
 from tabulate import tabulate
 
 
-class MCMCSummary(object):
+class MCMCSummary():
     """
     Calculates and prints key summaries of posterior samples and diagnostic
     quantities from MCMC chains.
diff --git a/pints/_nested/__init__.py b/pints/_nested/__init__.py
index 93c26e92d..f837cb033 100644
--- a/pints/_nested/__init__.py
+++ b/pints/_nested/__init__.py
@@ -227,7 +227,7 @@ def tell(self, fx):
         return proposed, winners
 
 
-class NestedController(object):
+class NestedController():
     """
     Uses nested sampling to sample from a posterior distribution.
 
diff --git a/pints/_optimisers/__init__.py b/pints/_optimisers/__init__.py
index cedc2213f..06ce225ac 100644
--- a/pints/_optimisers/__init__.py
+++ b/pints/_optimisers/__init__.py
@@ -336,7 +336,7 @@ def set_hyper_parameters(self, x):
         self.set_population_size(x[0])
 
 
-class OptimisationController(object):
+class OptimisationController():
     """
     Finds the parameter values that minimise an :class:`ErrorMeasure` or
     maximise a :class:`LogPDF`.
diff --git a/pints/_transformation.py b/pints/_transformation.py
index 2162a92bd..bfcee66a6 100644
--- a/pints/_transformation.py
+++ b/pints/_transformation.py
@@ -10,7 +10,7 @@
 from scipy.special import logit, expit
 
 
-class Transformation(object):
+class Transformation():
     """
     Abstract base class for objects that provide transformations between two
     parameter spaces: the model parameter space and a search space.
diff --git a/pints/_util.py b/pints/_util.py
index 5238c6532..4dceb9aec 100644
--- a/pints/_util.py
+++ b/pints/_util.py
@@ -17,7 +17,7 @@ def strfloat(x):
     return pints.FLOAT_FORMAT.format(float(x))
 
 
-class Timer(object):
+class Timer():
     """
     Provides accurate timing.
 
diff --git a/pints/tests/shared.py b/pints/tests/shared.py
index cbc14fd52..a3d12f25e 100644
--- a/pints/tests/shared.py
+++ b/pints/tests/shared.py
@@ -15,7 +15,7 @@
 import pints
 
 
-class StreamCapture(object):
+class StreamCapture():
     """
     A context manager that redirects and captures the output stdout, stderr,
     or both.
@@ -131,7 +131,7 @@ def text(self):
         return self._stderr_captured    # Could be None
 
 
-class SubCapture(object):
+class SubCapture():
     """
     A context manager that redirects and captures the standard and error output
     of the current process, using low-level file descriptor duplication.