diff --git a/nselib/datetime.lua b/nselib/datetime.lua
index 509d74253..a3cbf8677 100644
--- a/nselib/datetime.lua
+++ b/nselib/datetime.lua
@@ -41,6 +41,12 @@ function record_skew(host, timestamp, received)
   host.registry.datetime_skew = skew_tab
 end
 
+-- Work around Windows error formatting time zones where 1970/1/1 UTC was 1969/12/31
+system_time_at_epoch = (
+  time({year=1970, month=1, day=2, hour=0}) -- local time on 1970/1/2
+  - 86400 -- minus 1 day = local time at 1970/1/1
+  - time(date("!*t", 0)) -- minus UTC offset (Windows). On *nix this is 0.
+  )
 -- Find the offset in seconds between local time and UTC. That is, if we
 -- interpret a UTC date table as a local date table by passing it to os.time,
 -- how much must be added to the resulting integer timestamp to make it
@@ -70,9 +76,14 @@ end
 -- <code>
 -- date_to_timestamp({year=1970,month=1,day=1,hour=4,min=0,sec=0}, 1*60*60) --> 10800
 -- </code>
-function date_to_timestamp(date, offset)
+function date_to_timestamp(date_t, offset)
+  local status, tm = pcall(time, date_t)
+  if not status then
+    stdnse.debug1("Invalid date for this platform: %s", tm)
+    return nil
+  end
   offset = offset or 0
-  return time(date) + utc_offset(time(date)) - offset
+  return tm + utc_offset(tm) - offset
 end
 
 local function format_tz(offset)
@@ -124,15 +135,21 @@ function format_timestamp(t, offset)
     local status, result = pcall(date, "!%Y-%m-%dT%H:%M:%S", floor(t + offset))
     if not status then
       local tmp = floor(t + offset)
+      local extra_years
+      local seconds_in_year = 31556926
       if tmp > 0xffffffff then
         -- Maybe too far in the future?
-        local seconds_in_year = 31556926
-        local extra_years = (tmp  - 0xffffffff) // seconds_in_year + 1
+        extra_years = (tmp  - 0xffffffff) // seconds_in_year + 1
+      elseif tmp < system_time_at_epoch then
+        -- Windows can't display times before the epoch
+        extra_years = tmp // seconds_in_year
+      end
+      if extra_years then
         tmp = tmp - extra_years * seconds_in_year
         status, result = pcall(date, "!*t", tmp)
         if status then
           -- seconds_in_year is imprecise, so we truncate to date only
-          result = format("%d-%02d-%02d", result.year + extra_years, result.month, result.day)
+          result = format("%d-%02d-%02d?", result.year + extra_years, result.month, result.day)
         end
       end
     end
diff --git a/nselib/ldap.lua b/nselib/ldap.lua
index 8d46757b2..34eb67da9 100644
--- a/nselib/ldap.lua
+++ b/nselib/ldap.lua
@@ -824,7 +824,9 @@ end
 function convertADTimeStamp(timestamp)
 
   local result = 0
-  local base_time = tonumber(os.time({year=1601, month=1, day=1, hour=0, minute=0, sec =0}))
+  -- Windows cannot represent this time, so we pre-calculated it:
+  -- os.time({year=1601, month=1, day=1, hour=0, minute=0, sec =0})
+  local base_time = -11644473600
 
   timestamp = tonumber(timestamp)
 
diff --git a/nselib/mssql.lua b/nselib/mssql.lua
index f8e22b0df..d5bb155c5 100644
--- a/nselib/mssql.lua
+++ b/nselib/mssql.lua
@@ -106,7 +106,7 @@
 local math = require "math"
 local match = require "match"
 local nmap = require "nmap"
-local os = require "os"
+local datetime = require "datetime"
 local shortport = require "shortport"
 local smb = require "smb"
 local smbauth = require "smbauth"
@@ -156,6 +156,8 @@ do
   end
 end
 
+-- This constant is number of seconds from 1900-01-01 to 1970-01-01
+local tds_offset_seconds = -2208988800 + datetime.system_time_at_epoch
 
 -- *************************************
 -- Informational Classes
@@ -1231,19 +1233,13 @@ ColumnData =
     end,
 
     [DataTypes.SYBDATETIME] = function( data, pos )
-      local hi, lo, result_seconds, result
-      local tds_epoch, system_epoch, tds_offset_seconds
+      local hi, lo
 
       hi, lo, pos = string.unpack("<i4I4", data, pos)
 
-      tds_epoch = os.time( {year = 1900, month = 1, day = 1, hour = 00, min = 00, sec = 00, isdst = nil} )
-      -- determine the offset between the tds_epoch and the local system epoch
-      system_epoch       = os.time( os.date("*t", 0))
-      tds_offset_seconds = os.difftime(tds_epoch,system_epoch)
+      local result_seconds = (hi*24*60*60) + (lo/300)
 
-      result_seconds = (hi*24*60*60) + (lo/300)
-
-      result = os.date("!%b %d, %Y %H:%M:%S", tds_offset_seconds + result_seconds )
+      local result = datetime.format_timestamp(tds_offset_seconds + result_seconds)
       return pos, result
     end,
 
@@ -1311,23 +1307,6 @@ ColumnData =
       return ColumnData.Parse[DataTypes.DECIMALNTYPE]( precision, scale, data, pos )
     end,
 
-    [DataTypes.SYBDATETIME] = function( data, pos )
-      local hi, lo, result_seconds, result
-      local tds_epoch, system_epoch, tds_offset_seconds
-
-      hi, lo, pos = string.unpack("<i4I4", data, pos)
-
-      tds_epoch = os.time( {year = 1900, month = 1, day = 1, hour = 00, min = 00, sec = 00, isdst = nil} )
-      -- determine the offset between the tds_epoch and the local system epoch
-      system_epoch       = os.time( os.date("*t", 0))
-      tds_offset_seconds = os.difftime(tds_epoch,system_epoch)
-
-      result_seconds = (hi*24*60*60) + (lo/300)
-
-      result = os.date("!%b %d, %Y %H:%M:%S", tds_offset_seconds + result_seconds )
-      return pos, result
-    end,
-
     [DataTypes.BITNTYPE] = function( data, pos )
       return ColumnData.Parse[DataTypes.SYBINTN](data, pos)
     end,
@@ -1406,13 +1385,8 @@ ColumnData =
         local days, mins
         days, mins, pos = string.unpack("<I2I2", data, pos)
 
-        local tds_epoch = os.time( {year = 1900, month = 1, day = 1, hour = 00, min = 00, sec = 00, isdst = nil} )
-        -- determine the offset between the tds_epoch and the local system epoch
-        local system_epoch = os.time( os.date("*t", 0))
-        local tds_offset_seconds = os.difftime(tds_epoch,system_epoch)
-
         local result_seconds = (days*24*60*60) + (mins*60)
-        coldata = os.date("!%b %d, %Y %H:%M:%S", tds_offset_seconds + result_seconds )
+        coldata = datetime.format_timestamp(tds_offset_seconds + result_seconds)
 
         return pos,coldata