diff --git a/lib/vtt.js b/lib/vtt.js
index 2be9864..caf7bed 100644
--- a/lib/vtt.js
+++ b/lib/vtt.js
@@ -820,9 +820,10 @@ function moveBoxToLinePosition(window, styleBox, containerBox, boxPositions) {
         percentage = 1; // Highest possible so the first thing we get is better.
 
     for (var i = 0; i < axis.length; i++) {
+      var step = b.lineHeight > 0 ? b.lineHeight : 1;
       while (b.overlapsOppositeAxis(containerBox, axis[i]) ||
              (b.within(containerBox) && b.overlapsAny(boxPositions))) {
-        b.move(axis[i]);
+        b.move(axis[i], step);
       }
       // We found a spot where we aren't overlapping anything. This is our
       // best position.