diff --git a/src/ol/render/canvas/textreplay.js b/src/ol/render/canvas/textreplay.js
index 4b5b795d419..a16b34658b8 100644
--- a/src/ol/render/canvas/textreplay.js
+++ b/src/ol/render/canvas/textreplay.js
@@ -281,7 +281,7 @@ ol.render.canvas.TextReplay.prototype.drawText = function(geometry, feature) {
  */
 ol.render.canvas.TextReplay.prototype.getImage = function(text, textKey, fillKey, strokeKey) {
   var label;
-  var key = strokeKey + textKey + text + fillKey;
+  var key = strokeKey + textKey + this.pixelRatio + fillKey + text;
 
   var labelCache = ol.render.canvas.labelCache;
   if (!labelCache.containsKey(key)) {