diff --git a/src/ol/source/imagewmssource.js b/src/ol/source/imagewmssource.js
index 6f7d6ddd2a..dcc3596e8d 100644
--- a/src/ol/source/imagewmssource.js
+++ b/src/ol/source/imagewmssource.js
@@ -109,7 +109,9 @@ ol.source.ImageWMS.prototype.getFeatureInfoForPixel =
   var size = map.getSize();
   goog.asserts.assert(goog.isDefAndNotNull(size));
   var extent = view.calculateExtent(size);
-  var url = this.imageUrlFunction(extent, size, view.getProjection());
+  var projection = view.getProjection();
+  goog.asserts.assert(goog.isDef(projection));
+  var url = this.imageUrlFunction(extent, size, projection);
   goog.asserts.assert(goog.isDef(url),
       'ol.source.ImageWMS#imageUrlFunction does not return a URL');
   ol.source.wms.getFeatureInfo(url, pixel, this.getFeatureInfoOptions_, success,
diff --git a/src/ol/source/tilewmssource.js b/src/ol/source/tilewmssource.js
index 7f5e849cbb..67cb7467f5 100644
--- a/src/ol/source/tilewmssource.js
+++ b/src/ol/source/tilewmssource.js
@@ -157,11 +157,13 @@ ol.source.TileWMS.prototype.getFeatureInfoForPixel =
     function(pixel, map, success, opt_error) {
   var coord = map.getCoordinateFromPixel(pixel),
       view2D = map.getView().getView2D(),
-      projection = view2D.getProjection(),
-      tileGrid = goog.isNull(this.tileGrid) ?
-          ol.tilegrid.getForProjection(projection) : this.tileGrid,
-      tileCoord = tileGrid.getTileCoordForCoordAndResolution(coord,
-          view2D.getResolution()),
+      projection = view2D.getProjection();
+  goog.asserts.assert(goog.isDef(projection));
+  var tileGrid = goog.isNull(this.tileGrid) ?
+          ol.tilegrid.getForProjection(projection) : this.tileGrid;
+  var resolution = view2D.getResolution();
+  goog.asserts.assert(goog.isDef(resolution));
+  var tileCoord = tileGrid.getTileCoordForCoordAndResolution(coord, resolution),
       tileExtent = tileGrid.getTileCoordExtent(tileCoord),
       offset = map.getPixelFromCoordinate(ol.extent.getTopLeft(tileExtent)),
       url = this.tileUrlFunction(tileCoord, projection);