diff --git a/README.md b/README.md
index bbe2d2368f326d4771eddba2a5f0b4cdcc36fc98..fb17b69174a5244655ed3e7a1a9a47ddb9127473 100644
--- a/README.md
+++ b/README.md
@@ -44,7 +44,7 @@ $ git clone git@gitlab.aei.uni-hannover.de:GregAshton/PyFstat.git
 `pyfstat` makes uses the following external python modules:
 
 * [numpy](http://www.numpy.org/)
-* [matplotlib](http://matplotlib.org/)
+* [matplotlib](http://matplotlib.org/) >= 1.4
 * [scipy](https://www.scipy.org/)
 * [emcee](http://dan.iel.fm/emcee/current/)
 * [corner](https://pypi.python.org/pypi/corner/)
diff --git a/pyfstat/mcmc_based_searches.py b/pyfstat/mcmc_based_searches.py
index aae72a68c641819edf675eb56a8531f5c5c444d3..7bd26f0a9b17d8ab04856cc60a100a3bc40b66b2 100644
--- a/pyfstat/mcmc_based_searches.py
+++ b/pyfstat/mcmc_based_searches.py
@@ -771,9 +771,14 @@ class MCMCSearch(core.BaseSearchClass):
     def _plot_walkers(self, sampler, symbols=None, alpha=0.4, color="k",
                       temp=0, lw=0.1, nprod=0, add_det_stat_burnin=False,
                       fig=None, axes=None, xoffset=0, plot_det_stat=False,
-                      context='classic', subtractions=None, labelpad=0.05):
+                      context='ggplot', subtractions=None, labelpad=0.05):
         """ Plot all the chains from a sampler """
 
+        if context not in plt.style.available:
+            raise ValueError((
+                'The requested context {} is not available; please select a'
+                ' context from `plt.style.available`').format(context))
+
         if np.ndim(axes) > 1:
             axes = axes.flatten()
 
diff --git a/requirements.txt b/requirements.txt
index c34c50800322d36c45aa10ac0d5faa24e8dec9c4..02f6554599ffa80e880845a8b2a873ab256227d9 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -1,5 +1,5 @@
 numpy
-matplotlib
+matplotlib>=1.4
 scipy
 emcee
 corner