diff --git a/src/Handler/Utils/Exam.hs b/src/Handler/Utils/Exam.hs
index ef6050f7e..dfc895c92 100644
--- a/src/Handler/Utils/Exam.hs
+++ b/src/Handler/Utils/Exam.hs
@@ -535,7 +535,7 @@ examAutoOccurrence (hash -> seed) rule ExamAutoOccurrenceConfig{..} occurrences
     postprocess result = seq resultAscList (resultAscList, resultUsers)
       where
         maxTagLength :: Int
-        maxTagLength = maximum $ map (length . snd) result
+        maxTagLength = maybe 0 maximum $ fromNullable $ map (length . snd) result
 
         rangeAlphabet :: [CI Char]
         rangeAlphabet = case rule of
@@ -565,7 +565,7 @@ examAutoOccurrence (hash -> seed) rule ExamAutoOccurrenceConfig{..} occurrences
                   | length start < maxTagLength
                   = go (impureNonNull $ replicate (succ $ length start) $ head alphabet) [] result
                   | otherwise
-                  = Map.empty
+                  = []
                   where
                     mappingDescription :: ExamOccurrenceMappingDescription
                     mappingDescription = ExamOccurrenceMappingRange (toNullable start) end
@@ -592,10 +592,10 @@ examAutoOccurrence (hash -> seed) rule ExamAutoOccurrenceConfig{..} occurrences
                     increase :: [CI Char] -> [CI Char]
                     increase [] = []
                     increase (c:cs)
+                      | c < head alphabet
+                      = head alphabet : cs
                       | nextChar == head alphabet
                       = nextChar : increase cs
-                      | nextChar == paddingChar
-                      = head alphabet : cs
                       | otherwise
                       = nextChar : cs
                       where
@@ -603,9 +603,7 @@ examAutoOccurrence (hash -> seed) rule ExamAutoOccurrenceConfig{..} occurrences
                         nextChar
                           | c `elem` alphabet
                           = dropWhile (/= c) alphabetCycle List.!! 1
-                          | c < head alphabet -- includes padding char
-                          = head alphabet
-                          | c > last alphabet -- basically all non-ascii printable characters
+                          | otherwise -- includes padding char
                           = head alphabet
                       -- TODO what if the border is between to non-ascii characters?
         
diff --git a/test/Handler/Utils/ExamSpec.hs b/test/Handler/Utils/ExamSpec.hs
index c6a431222..9de995308 100644
--- a/test/Handler/Utils/ExamSpec.hs
+++ b/test/Handler/Utils/ExamSpec.hs
@@ -193,7 +193,7 @@ spec = do
                     , "Martin", "Jackson", "Thompson", "White"
                     , "Lopez", "Lee", "Gonzalez", "Harris"
                     , "Clark", "Lewis", "Robinson", "Walker"
-                    , "Perez", "Hall", "Young", "zu Allen"
+                    , "Perez", "Hall", "Young", "zu Allen", "Fu"
                     , "Únîcòdé", "Ähm-Ümlaüte", "von Leerzeichen"
                     ]
         occurrenceMap :: Map UserId (Maybe ExamOccurrenceId) -> Map ExamOccurrenceId [UserId]