diff --git a/src/Handler/Exam/AutoOccurrence.hs b/src/Handler/Exam/AutoOccurrence.hs
index b4ee68dd5..e0388dc95 100644
--- a/src/Handler/Exam/AutoOccurrence.hs
+++ b/src/Handler/Exam/AutoOccurrence.hs
@@ -62,7 +62,7 @@ examAutoOccurrenceCalculateForm ExamAutoOccurrenceCalculateForm{ eaofConfig }
     automaticIfTrue False = EAOIRManual Set.empty
     ignoreRooms :: ExamAutoOccurrenceIgnoreRooms -> Bool
     ignoreRooms EAOIRAutomatic = True
-    ignoreRooms (EAOIRManual s) = null s
+    ignoreRooms (EAOIRManual s) = not $ null s
 
 examAutoOccurrenceNudgeForm :: ExamOccurrenceId -> Maybe ExamAutoOccurrenceCalculateForm -> Form ExamAutoOccurrenceCalculateForm
 examAutoOccurrenceNudgeForm occId protoForm html = do
diff --git a/src/Handler/Utils/Exam.hs b/src/Handler/Utils/Exam.hs
index e8f8c6b1c..2000aeb25 100644
--- a/src/Handler/Utils/Exam.hs
+++ b/src/Handler/Utils/Exam.hs
@@ -413,7 +413,7 @@ examAutoOccurrence (hash -> seed) rule ExamAutoOccurrenceConfig{..} occurrences
     -- If a single occurrence can accommodate all participants, pick the one with
     -- the least capacity
     (occurrences'', ignoredOccurrences) = case eaocIgnoreRooms of
-      (EAOIRManual manuallyIgnored) -> (Map.toList $ Map.restrictKeys occurrences' manuallyIgnored, manuallyIgnored)
+      (EAOIRManual manuallyIgnored) -> (Map.toList $ Map.withoutKeys occurrences' manuallyIgnored, manuallyIgnored)
       EAOIRAutomatic -- effect of ticked minimizeRooms Checkbox
         | Just largeEnoughs <- fromNullable . filter ((>= Restricted usersCount) . view _2) $ Map.toList occurrences'
         -> let pickedLargeEnough = minimumBy (comparing $ view _2) largeEnoughs