diff --git a/darshan-util/pydarshan/darshan/backend/cffi_backend.py b/darshan-util/pydarshan/darshan/backend/cffi_backend.py
index f8794ce36..2aff63d64 100644
--- a/darshan-util/pydarshan/darshan/backend/cffi_backend.py
+++ b/darshan-util/pydarshan/darshan/backend/cffi_backend.py
@@ -739,7 +739,7 @@ def _df_to_rec(rec_dict, mod_name, rec_index_of_interest=None):
     return buf
 
 
-def accumulate_records(rec_dict, mod_name, nprocs, dtype='numpy'):
+def accumulate_records(rec_dict, mod_name, nprocs):
     """
     Passes a set of records (in pandas format) to the Darshan accumulator
     interface, and returns the corresponding derived metrics struct and
@@ -789,5 +789,5 @@ def accumulate_records(rec_dict, mod_name, nprocs, dtype='numpy'):
                            "to retrieve additional information from the stderr "
                            "stream.")
 
-    summary_rec = _make_generic_record(summary_rbuf, mod_name, dtype)
+    summary_rec = _make_generic_record(summary_rbuf, mod_name, dtype='pandas')
     return derived_metrics, summary_rec
diff --git a/darshan-util/pydarshan/darshan/cli/summary.py b/darshan-util/pydarshan/darshan/cli/summary.py
index 67afc42a2..319f7390f 100644
--- a/darshan-util/pydarshan/darshan/cli/summary.py
+++ b/darshan-util/pydarshan/darshan/cli/summary.py
@@ -506,7 +506,7 @@ def register_figures(self):
                     # record and derived metrics
                     rec_dict = self.report.records[mod].to_df()
                     nprocs = self.report.metadata['job']['nprocs']
-                    derived_metrics, summary_record = accumulate_records(rec_dict, mod, nprocs, dtype='pandas')
+                    derived_metrics, summary_record = accumulate_records(rec_dict, mod, nprocs)
 
                     # this is really just some text
                     # so using ReportFigure feels awkward...