diff --git a/Signal/src/ViewControllers/ConversationView/MessagesViewController.m b/Signal/src/ViewControllers/ConversationView/MessagesViewController.m
index 1b7806e1c..2c97a138c 100644
--- a/Signal/src/ViewControllers/ConversationView/MessagesViewController.m
+++ b/Signal/src/ViewControllers/ConversationView/MessagesViewController.m
@@ -4501,6 +4501,11 @@ typedef NS_ENUM(NSInteger, MessagesRangeSizeMode) {
 {
     OWSAssert([NSThread isMainThread]);
 
+    // JSQMessageView has glitchy behavior. When presenting/dismissing view
+    // controllers, the size of the input toolbar and/or collection view can
+    // repeatedly change, leaving scroll state in an invalid state.  The
+    // simplest fix that covers most cases is to ensure that we remain
+    // "scrolled to bottom" across these changes.
     if (self.wasScrolledToBottomBeforeLayoutChange) {
         [self scrollToBottomImmediately];
     }