diff --git a/rank_progress.py b/rank_progress.py
--- a/rank_progress.py
+++ b/rank_progress.py
@@ -36,6 +36,7 @@ class Record:
 
 class RankTracker:
 	def __init__(self, rating):
+		assert rating >= -900
 		self._rounded_rating = round_rating(rating)
 
 	@property
@@ -43,22 +44,24 @@ class RankTracker:
 		return rating_to_rank(self._rounded_rating)
 
 	def update(self, rating):
+		assert rating >= -900
 		rounded_rating = round_rating(rating)
+		old_rank = self.rank
 
 		if rounded_rating == self._rounded_rating:
-			return False
+			pass
 		elif rounded_rating > self._rounded_rating:  # promotion
 			self._rounded_rating = rounded_rating
-			return self.rank
 		else:  # demotion
-			if rounded_rating >= 1500 and self._rounded_rating - rating > 100:
+			if self._rounded_rating >= 1600 and self._rounded_rating - rating > 100:
 				self._rounded_rating = rounded_rating
-				return self.rank
 			elif self._rounded_rating - rating > 150:
 				self._rounded_rating = rounded_rating+100
-				return self.rank
 			else:
-				return False
+				pass
+
+		new_rank = self.rank
+		return new_rank if new_rank != old_rank else False
 
 
 def parse_record(record):