diff --git a/lib/mixins/canvas-drawer.coffee b/lib/mixins/canvas-drawer.coffee
index 9378ed21..999091dc 100644
--- a/lib/mixins/canvas-drawer.coffee
+++ b/lib/mixins/canvas-drawer.coffee
@@ -307,6 +307,10 @@ class CanvasDrawer extends Mixin
     for change in @pendingChanges
       newIntactRanges = []
       for range in intactRanges
+        if isNaN(change.screenDelta)
+          debugger if atom.inDevMode()
+          change.screenDelta = change.end - change.start
+
         if change.end < range.start and change.screenDelta != 0
           newIntactRanges.push(
             start: range.start + change.screenDelta