diff --git a/bilby/bilby_mcmc/sampler.py b/bilby/bilby_mcmc/sampler.py
index 67bd076482fda6c26f32d48f95d47f8800265a36..32e615bdfb9474bfb19857b601e6e114defe4d12 100644
--- a/bilby/bilby_mcmc/sampler.py
+++ b/bilby/bilby_mcmc/sampler.py
@@ -251,8 +251,8 @@ class Bilby_MCMC(MCMCSampler):
     @staticmethod
     def add_data_to_result(result, ptsampler, outdir, label, make_plots):
         result.samples = ptsampler.samples
-        result.log_likelihood_evaluations = result.samples[LOGLKEY]
-        result.log_prior_evaluations = result.samples[LOGPKEY]
+        result.log_likelihood_evaluations = result.samples[LOGLKEY].to_numpy()
+        result.log_prior_evaluations = result.samples[LOGPKEY].to_numpy()
         ptsampler.compute_evidence(
             outdir=outdir,
             label=label,
diff --git a/bilby/core/utils/io.py b/bilby/core/utils/io.py
index 190f55ea4af4d31af9435fc6732c90a4bd1db642..6d1482714cfb947c4d073a9dbc151e755d407cfd 100644
--- a/bilby/core/utils/io.py
+++ b/bilby/core/utils/io.py
@@ -292,8 +292,6 @@ def encode_for_hdf5(key, item):
         output = json.dumps(item._get_json_dict())
     elif isinstance(item, pd.DataFrame):
         output = item.to_dict(orient="list")
-    elif isinstance(item, pd.Series):
-        output = item.to_dict()
     elif inspect.isfunction(item) or inspect.isclass(item):
         output = dict(
             __module__=item.__module__, __name__=item.__name__, __class__=True