diff --git a/src/Handler/Term.hs b/src/Handler/Term.hs
index ec0f615ad..ff57fc8ce 100644
--- a/src/Handler/Term.hs
+++ b/src/Handler/Term.hs
@@ -19,37 +19,13 @@ import qualified Data.Set as Set
 
 import qualified Control.Monad.State.Class as State
 
-import Data.Time.Calendar.WeekDate
-
-
-data TermDay
-  = TermDayStart | TermDayEnd
-  | TermDayLectureStart | TermDayLectureEnd
-  deriving (Eq, Ord, Read, Show, Enum, Bounded, Generic, Typeable)
-  deriving anyclass (Universe, Finite)
-
-guessDay :: TermIdentifier
-         -> TermDay
-         -> Day
-guessDay TermIdentifier{ year, season = Q1 } TermDayStart  = fromGregorian year  1  1
-guessDay TermIdentifier{ year, season = Q1 } TermDayEnd    = fromGregorian year  3 31
-guessDay TermIdentifier{ year, season = Q2 } TermDayStart  = fromGregorian year  4  1
-guessDay TermIdentifier{ year, season = Q2 } TermDayEnd    = fromGregorian year  6 30
-guessDay TermIdentifier{ year, season = Q3 } TermDayStart  = fromGregorian year  7  1
-guessDay TermIdentifier{ year, season = Q3 } TermDayEnd    = fromGregorian year  9 30
-guessDay TermIdentifier{ year, season = Q4 } TermDayStart  = fromGregorian year 10  1
-guessDay TermIdentifier{ year, season = Q4 } TermDayEnd    = fromGregorian year 12 31
-guessDay tid@TermIdentifier{ year } TermDayLectureStart = fromWeekDate year weekStart 1 -- first Monday within Quarter
-  where (_, weekStart, _) = toWeekDate $ guessDay tid TermDayStart
-guessDay tid@TermIdentifier{ year } TermDayLectureEnd   = fromWeekDate year weekStart 5 -- Friday of last week within Quarter
-  where (_, weekStart, _) = toWeekDate $ guessDay tid TermDayEnd
 
 
 validateTerm :: (MonadHandler m, HandlerSite m ~ UniWorX)
              => FormValidator TermForm m ()
 validateTerm = do
   TermForm{..} <- State.get
-  guardValidation MsgTermStartMustMatchName $ tfStart `withinTerm` tfName
+  guardValidation MsgTermStartMustMatchName $ tfStart `withinTermYear` tfName
   guardValidation MsgTermEndMustBeAfterStart $ tfStart < tfEnd
   guardValidation MsgTermLectureEndMustBeAfterStart $ tfLectureStart < tfLectureEnd
   guardValidation MsgTermStartMustBeBeforeLectureStart $ tfStart <= tfLectureStart
diff --git a/src/Model/Types/DateTime.hs b/src/Model/Types/DateTime.hs
index cfb6f0ed1..218dd202b 100644
--- a/src/Model/Types/DateTime.hs
+++ b/src/Model/Types/DateTime.hs
@@ -16,6 +16,8 @@ import qualified Data.CaseInsensitive as CI
 import Data.Either.Combinators (maybeToRight)
 import Text.Read (readMaybe)
 
+import Data.Time.Calendar.WeekDate
+
 import Database.Persist.Sql
 
 import Web.HttpApiData
@@ -31,7 +33,7 @@ data Season = Q1 | Q2 | Q3 | Q4
   deriving anyclass (Binary, Universe, Finite, NFData)
 
 numSeasons :: Int -- to be flexible
-numSeasons = fromEnum(maxBound::Season)
+numSeasons = succ $ fromEnum(maxBound::Season)
 
 seasonFromText' :: Text -> Either Text Season
 seasonFromText' t = maybeToRight errmsg (readMaybe $ Text.unpack $ Text.toUpper t)
@@ -159,9 +161,31 @@ pathPieceCsv ''TermIdentifier
    See Handler.Utils.Form.termsField and termActiveField
 -}
 
+data TermDay
+  = TermDayStart | TermDayEnd
+  | TermDayLectureStart | TermDayLectureEnd
+  deriving (Eq, Ord, Read, Show, Enum, Bounded, Generic, Typeable)
+  deriving anyclass (Universe, Finite)
 
-withinTerm :: Day -> TermIdentifier -> Bool
-time `withinTerm` term = timeYear `mod` 100 == termYear `mod` 100
+guessDay :: TermIdentifier
+         -> TermDay
+         -> Day
+guessDay TermIdentifier{ year, season = Q1 } TermDayStart  = fromGregorian year  1  1
+guessDay TermIdentifier{ year, season = Q2 } TermDayStart  = fromGregorian year  4  1
+guessDay TermIdentifier{ year, season = Q3 } TermDayStart  = fromGregorian year  7  1
+guessDay TermIdentifier{ year, season = Q4 } TermDayStart  = fromGregorian year 10  1
+guessDay tid TermDayEnd = pred $ guessDay (succ tid) TermDayStart
+guessDay tid@TermIdentifier{ year } TermDayLectureStart = fromWeekDate year weekStart 1 -- first Monday within Quarter
+  where (_, weekStart, _) = toWeekDate $ guessDay tid TermDayStart
+guessDay tid@TermIdentifier{ year } TermDayLectureEnd   = fromWeekDate year weekStart 5 -- Friday of last week within Quarter
+  where (_, weekStart, _) = toWeekDate $ guessDay tid TermDayEnd
+
+withinTerm :: Day -> TermIdentifier -> Bool 
+withinTerm d tid = guessDay tid TermDayStart <= d && d <= guessDay tid TermDayEnd
+
+-- | Check only if last two digits within the year numbers match
+withinTermYear :: Day -> TermIdentifier -> Bool
+time `withinTermYear` term = timeYear `mod` 100 == termYear `mod` 100
   where
     timeYear = fst3 $ toGregorian time
     termYear = year term