diff --git a/src/Handler/Utils/Exam.hs b/src/Handler/Utils/Exam.hs
index 8d0856f61..ef6050f7e 100644
--- a/src/Handler/Utils/Exam.hs
+++ b/src/Handler/Utils/Exam.hs
@@ -534,14 +534,15 @@ examAutoOccurrence (hash -> seed) rule ExamAutoOccurrenceConfig{..} occurrences
                    )
     postprocess result = seq resultAscList (resultAscList, resultUsers)
       where
+        maxTagLength :: Int
+        maxTagLength = maximum $ map (length . snd) result
+
         rangeAlphabet :: [CI Char]
-        rangeAlphabet
-          | ExamRoomSurname <- rule
-          = map CI.mk ['A'..'Z']
-          | ExamRoomMatriculation <- rule
-          = map CI.mk ['0'..'9']
-          | otherwise
-          = []
+        rangeAlphabet = case rule of
+          ExamRoomSurname -> map CI.mk ['A'..'Z']
+          -- ExamRoomSurname -> map CI.mk [c | c <- universeF, isPrint c]  -- all printable unicode characters
+          ExamRoomMatriculation-> map CI.mk ['0'..'9']
+          _rule -> []
 
         resultAscList :: Map ExamOccurrenceId (Set ExamOccurrenceMappingDescription)
         resultAscList = case fromNullable rangeAlphabet of
@@ -559,8 +560,12 @@ examAutoOccurrence (hash -> seed) rule ExamAutoOccurrenceConfig{..} occurrences
                     eaomrEnd = replicate (length start) $ last alphabet
                 go start acc ((_occurrenceId, []):t) = go start acc t
                 go start acc ((occurrenceId, userTags):t)
-                  | matchMappingDescription mappingDescription userTags = go nextStart ((occurrenceId, mappingDescription) : acc) t
-                  | otherwise = go (impureNonNull $ replicate (succ $ length start) $ head alphabet) [] result
+                  | matchMappingDescription mappingDescription userTags
+                  = go nextStart ((occurrenceId, mappingDescription) : acc) t
+                  | length start < maxTagLength
+                  = go (impureNonNull $ replicate (succ $ length start) $ head alphabet) [] result
+                  | otherwise
+                  = Map.empty
                   where
                     mappingDescription :: ExamOccurrenceMappingDescription
                     mappingDescription = ExamOccurrenceMappingRange (toNullable start) end
@@ -595,7 +600,14 @@ examAutoOccurrence (hash -> seed) rule ExamAutoOccurrenceConfig{..} occurrences
                       = nextChar : cs
                       where
                         nextChar :: CI Char
-                        nextChar = dropWhile (/= c) alphabetCycle List.!! 1
+                        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
+                          = head alphabet
+                      -- TODO what if the border is between to non-ascii characters?
         
         transformTag :: (MonoFoldable f) => f -> [CI Char] -> [CI Char]
         transformTag (length -> l) tag = case rule of