diff --git a/spec/lines-yardstick-spec.coffee b/spec/lines-yardstick-spec.coffee
index fbf5c53bf..44267699e 100644
--- a/spec/lines-yardstick-spec.coffee
+++ b/spec/lines-yardstick-spec.coffee
@@ -57,7 +57,10 @@ describe "LinesYardstick", ->
           textNodes
 
       editor.setLineHeightInPixels(14)
-      linesYardstick = new LinesYardstick(editor, mockPresenter, mockLineNodesProvider, new LineTopIndex(), atom.grammars)
+      lineTopIndex = new LineTopIndex()
+      lineTopIndex.setDefaultLineHeight(editor.getLineHeightInPixels())
+      lineTopIndex.setMaxRow(editor.getScreenLineCount())
+      linesYardstick = new LinesYardstick(editor, mockPresenter, mockLineNodesProvider, lineTopIndex, atom.grammars)
 
   afterEach ->
     lineNode.remove() for lineNode in createdLineNodes
diff --git a/src/lines-yardstick.coffee b/src/lines-yardstick.coffee
index c1faa6399..847ebfd46 100644
--- a/src/lines-yardstick.coffee
+++ b/src/lines-yardstick.coffee
@@ -25,6 +25,7 @@ class LinesYardstick
     row = @lineTopIndex.rowForTopPixelPosition(targetTop, 'floor')
     targetLeft = 0 if targetTop < 0
     targetLeft = Infinity if row > @model.getLastScreenRow()
+    row = Math.min(row, @model.getLastScreenRow())
 
     @prepareScreenRowsForMeasurement([row]) unless measureVisibleLinesOnly