diff --git a/src/ol/render/canvas/canvasreplay.js b/src/ol/render/canvas/canvasreplay.js
index f08d633d2c..dd5f15a979 100644
--- a/src/ol/render/canvas/canvasreplay.js
+++ b/src/ol/render/canvas/canvasreplay.js
@@ -2005,7 +2005,8 @@ ol.render.canvas.ReplayGroup.prototype.getReplay =
   if (!goog.isDef(replay)) {
     var Constructor = ol.render.canvas.BATCH_CONSTRUCTORS_[replayType];
     goog.asserts.assert(goog.isDef(Constructor),
-        'Constructor should be defined');
+        replayType +
+        ' constructor missing from ol.render.canvas.BATCH_CONSTRUCTORS_');
     replay = new Constructor(this.tolerance_, this.maxExtent_,
         this.resolution_);
     replays[replayType] = replay;
diff --git a/src/ol/render/webgl/webglreplay.js b/src/ol/render/webgl/webglreplay.js
index 97322c7c9d..8c2590c63d 100644
--- a/src/ol/render/webgl/webglreplay.js
+++ b/src/ol/render/webgl/webglreplay.js
@@ -1085,7 +1085,8 @@ ol.render.webgl.ReplayGroup.prototype.getReplay =
   if (!goog.isDef(replay)) {
     var constructor = ol.render.webgl.BATCH_CONSTRUCTORS_[replayType];
     goog.asserts.assert(goog.isDef(constructor),
-        'a constructor could be found in ol.render.webgl.BATCH_CONSTRUCTORS_');
+        replayType +
+        ' constructor missing from ol.render.webgl.BATCH_CONSTRUCTORS_');
     replay = new constructor(this.tolerance_, this.maxExtent_);
     this.replays_[replayType] = replay;
   }