diff --git a/test/Handler/Utils/ExamSpec.hs b/test/Handler/Utils/ExamSpec.hs
index d15fb8726..d9fdd718e 100644
--- a/test/Handler/Utils/ExamSpec.hs
+++ b/test/Handler/Utils/ExamSpec.hs
@@ -14,6 +14,7 @@ import qualified Data.Map as Map
 import qualified Data.Set as Set
 import qualified Data.Text as Text
 import qualified Data.CaseInsensitive as CI
+import qualified Data.Foldable as Foldable
 
 import qualified Data.RFC5051 as RFC5051
 
@@ -332,14 +333,14 @@ spec = do
         mappingImpossiblePlausible :: ExamOccurrenceRule -> Map UserId (UserProperties, Maybe ExamOccurrenceId) -> Map ExamOccurrenceId Natural -> Bool
         mappingImpossiblePlausible
             rule
-            userProperties@(sort . map (ruleProperty rule . fst) . Map.elems . relevantUsers rule -> users')
+            userProperties@(sortBy RFC5051.compareUnicode . mapRuleProperty rule . Map.elems . relevantUsers rule -> users')
             (map snd . Map.toList . adjustOccurrences userProperties -> occurrences') = go 0 users' occurrences'
             where
                 smallestRoom :: Natural
                 smallestRoom = maybe 0 minimum $ fromNullable occurrences'
                 -- If there exists a bucket with the same tag bigger than the smallest room a nullResult might be returned
                 -- It may still work, but is not guaranteed (e.g. both the first bucket)
-                go :: Natural -> [Maybe Text] -> [Natural] -> Bool
+                go :: forall a. Eq a => Natural -> [a] -> [Natural] -> Bool
                 go biggestUserBucket [] _occurrences = biggestUserBucket > smallestRoom
                 go _biggestUserBucket _remainingUsers [] = True
                 go biggestUserBucket remainingUsers (0:t) = go biggestUserBucket remainingUsers t
@@ -350,13 +351,18 @@ spec = do
                     = go biggestUserBucket remainingUsers laterOccurrences
                     where
                         nextUsers :: Natural
-                        remainingUsers' :: [Maybe Text]
+                        remainingUsers' :: [a]
                         (fromIntegral . length -> nextUsers, remainingUsers') = span (== h) remainingUsers
-        ruleProperty :: ExamOccurrenceRule -> UserProperties -> Maybe Text
-        ruleProperty rule = case rule of
-            ExamRoomSurname -> Just . userSurname . user
-            ExamRoomMatriculation -> userMatrikelnummer . user
-            _rule -> const Nothing
+        mapRuleProperty :: ExamOccurrenceRule -> [(UserProperties, b)] -> [Text]
+        mapRuleProperty rule (map fst -> users') = map (ruleProperty rule minMatrLength) users'
+            where
+                minMatrLength :: Int
+                minMatrLength = Foldable.minimum $ map (maybe 0 Text.length . userMatrikelnummer . user) users'
+        ruleProperty :: ExamOccurrenceRule -> Int -> UserProperties -> Text
+        ruleProperty rule n = case rule of
+            ExamRoomSurname -> userSurname . user
+            ExamRoomMatriculation -> maybe Text.empty (Text.takeEnd n) . userMatrikelnummer . user
+            _rule -> const $ pack $ show rule
         -- copied and adjusted from Hander.Utils.Exam
         adjustOccurrences :: Map UserId (UserProperties, Maybe ExamOccurrenceId) -> Map ExamOccurrenceId Natural -> Map ExamOccurrenceId Natural
         -- ^ reduce room capacity for every pre-assigned user by 1