diff --git a/openquake/calculators/preclassical.py b/openquake/calculators/preclassical.py
index 8b96da16dec1..27b31ee8ec35 100644
--- a/openquake/calculators/preclassical.py
+++ b/openquake/calculators/preclassical.py
@@ -178,7 +178,7 @@ def store_tiles(dstore, csm, sitecol, cmakers):
          for cm, tgets, blocks, splits in quartets],
         [('grp_id', U16), ('gsims', U16), ('tiles', U16), ('blocks', U16),
          ('splits', U16), ('size_mb', F32), ('weight', F32),
-         ('codes', '<S8'), ('trt', '<S20')])
+         ('codes', '<S8'), ('trt', '<S32')])
 
     # determine light groups and tiling
     light, = numpy.where(data['blocks'] == 1)
diff --git a/openquake/hazardlib/tests/gsim/utils.py b/openquake/hazardlib/tests/gsim/utils.py
index db0e23ec82ac..13ded276229d 100644
--- a/openquake/hazardlib/tests/gsim/utils.py
+++ b/openquake/hazardlib/tests/gsim/utils.py
@@ -214,6 +214,8 @@ def check(self, *filenames, max_discrep_percentage,
             if sdt in gsim.DEFINED_FOR_STANDARD_DEVIATION_TYPES:
                 out_types.append(sdt.upper().replace(' ', '_') + '_STDDEV')
         cmaker, df = read_cmaker_df(gsim, fnames)
+        if len(df.result_type.unique()) > 1:
+            breakpoint()
         if truncation_level != 99.:
             cmaker.truncation_level = truncation_level
         for ctx in gen_ctxs(df):
diff --git a/utils/build_vtable b/utils/build_vtable
index 6188a55b73a6..ee3ba1c4e6e9 100755
--- a/utils/build_vtable
+++ b/utils/build_vtable
@@ -3,7 +3,7 @@ import sys
 import numpy as np
 import pandas
 from itertools import product
-from openquake.hazardlib import imt, valid, contexts
+from openquake.hazardlib import valid, contexts
 
 RES_INDEX = dict(MEAN=0, TOTAL_STDDEV=1,
                  INTER_EVENT_STDDEV=2, INTRA_EVENT_STDDEV=3)