diff --git a/bin/wee_database b/bin/wee_database
index 9e52f123..305ecc82 100755
--- a/bin/wee_database
+++ b/bin/wee_database
@@ -15,14 +15,11 @@ import sys
 import time
 
 from datetime import datetime as dt
-from distutils.version import StrictVersion
 
 # weewx imports
 import user.extensions      #@UnusedImport
-import weecfg
 import weecfg.patch
 import weedb
-import weewx
 import weewx.manager
 import weewx.units
 
diff --git a/bin/weecfg/patch.py b/bin/weecfg/patch.py
index 8a60979d..7c453bd3 100644
--- a/bin/weecfg/patch.py
+++ b/bin/weecfg/patch.py
@@ -20,7 +20,6 @@ import weedb
 import weewx
 
 from weeutil.weeutil import archiveDaySpan, genDaySpans, timestamp_to_string, startOfDay, min_with_none, tobool
-from weewx import require_weewx_version
 
 
 # ============================================================================
@@ -325,7 +324,8 @@ class IntervalWeighting(DatabasePatch):
                         if not self.dry_run:
                             self.dbm._set_day_summary(_day_accum,
                                                       _day_span.stop,
-                                                      _cursor)
+                                                      _cursor,
+                                                      check_version=False)
                         _days += 1
                         # Save the ts of the patched daily summary as the
                         # 'lastSummaryPatched' value in the archive_day__metadata
diff --git a/bin/weewx/manager.py b/bin/weewx/manager.py
index c4ae9c9e..efb68833 100644
--- a/bin/weewx/manager.py
+++ b/bin/weewx/manager.py
@@ -1127,8 +1127,8 @@ class DaySummaryManager(Manager):
         meta_name = '%s_day__metadata' % self.table_name
         self.daykeys = [x[Nprefix:] for x in all_tables if (x.startswith(prefix) and x != meta_name)]
         self.version = self._getVersion()
-        if self.version is None:
-            self.version = "2.0"
+        if weewx.debug:
+            assert(self.version is not None)
 
     def _initialize_day_tables(self, archiveSchema, cursor):  # @UnusedVariable
         """Initialize the tables needed for the daily summary."""
@@ -1573,7 +1573,7 @@ class DaySummaryManager(Manager):
             if not cursor:
                 _cursor.close()
 
-    def _set_day_summary(self, day_accum, lastUpdate, cursor):
+    def _set_day_summary(self, day_accum, lastUpdate, cursor, check_version=True):
         """Write all statistics for a day to the database in a single transaction.
         
         day_accum: an accumulator with the daily summary. See weewx.accum
@@ -1582,6 +1582,9 @@ class DaySummaryManager(Manager):
         Normally, this is the timestamp of the last archive record added to the instance
         day_accum. """
 
+        if check_version and self.version < '2.0':
+            raise weewx.ViolatedPrecondition("DaySummaryManager requires >= V2.0. You have '%s'" % self.version)
+
         # Make sure the new data uses the same unit system as the database.
         self._check_unit_system(day_accum.unit_system)