diff --git a/sql/field.cc b/sql/field.cc
index 6e45d10d855..de34b681a28 100644
--- a/sql/field.cc
+++ b/sql/field.cc
@@ -6796,7 +6796,12 @@ int Field_datetime::set_time()
   THD *thd= table->in_use;
   set_notnull();
   // Here we always truncate (not round), no matter what sql_mode is
-  store_datetime(Datetime(thd, thd->query_start_timeval()).trunc(decimals()));
+  if (decimals())
+    store_datetime(Datetime(thd, Timeval(thd->query_start(),
+                                         thd->query_start_sec_part())
+                            ).trunc(decimals()));
+  else
+    store_datetime(Datetime(thd, Timeval(thd->query_start(), 0)));
   return 0;
 }
 
diff --git a/sql/sql_class.h b/sql/sql_class.h
index d6da0566bbe..1fc4f375b6c 100644
--- a/sql/sql_class.h
+++ b/sql/sql_class.h
@@ -3455,10 +3455,6 @@ public:
   inline ulong query_start_sec_part()
   { query_start_sec_part_used=1; return start_time_sec_part; }
   MYSQL_TIME query_start_TIME();
-  Timeval query_start_timeval()
-  {
-    return Timeval(query_start(), query_start_sec_part());
-  }
   time_round_mode_t temporal_round_mode() const
   {
     return variables.sql_mode & MODE_TIME_ROUND_FRACTIONAL ?