diff --git a/lib/misc.lua b/lib/misc.lua
index cd07596..bf11647 100644
--- a/lib/misc.lua
+++ b/lib/misc.lua
@@ -8,17 +8,17 @@ function parse_hex_color(text)
 end
 
 function parse_iso8601_date(json_date)
-    local pattern = "(%d+)%-(%d+)%-(%d+)%a(%d+)%:(%d+)%:([%d%.]+)([Z%+%-])(%d?%d?)%:?(%d?%d?)"
+    local pattern = "(%d+)%-(%d+)%-(%d+)%a(%d+)%:(%d+)%:([%d%.]+)([Z%+%-]?)(%d?%d?)%:?(%d?%d?)"
     local year, month, day, hour, minute,
         seconds, offsetsign, offsethour, offsetmin = json_date:match(pattern)
     local timestamp = os.time{year = year, month = month,
         day = day, hour = hour, min = minute, sec = seconds}
     local offset = 0
-    if offsetsign ~= 'Z' then
+    if offsetsign ~= '' and offsetsign ~= 'Z' then
       offset = tonumber(offsethour) * 60 + tonumber(offsetmin)
       if xoffset == "-" then offset = offset * -1 end
     end
 
-    return timestamp + offset
+    return timestamp + offset * 60
 end