diff --git a/src/ol/format/jsonfeatureformat.js b/src/ol/format/jsonfeatureformat.js
index 6500d48e59..24ba4c39b0 100644
--- a/src/ol/format/jsonfeatureformat.js
+++ b/src/ol/format/jsonfeatureformat.js
@@ -26,11 +26,11 @@ ol.inherits(ol.format.JSONFeature, ol.format.Feature);
  * @return {Object} Object.
  */
 ol.format.JSONFeature.prototype.getObject_ = function(source) {
-  if (goog.isObject(source)) {
-    return source;
-  } else if (typeof source === 'string') {
+  if (typeof source === 'string') {
     var object = JSON.parse(source);
     return object ? /** @type {Object} */ (object) : null;
+  } else if (source !== null) {
+    return source;
   } else {
     goog.asserts.fail();
     return null;
diff --git a/src/ol/map.js b/src/ol/map.js
index 07ca935116..6d4021db3d 100644
--- a/src/ol/map.js
+++ b/src/ol/map.js
@@ -1486,7 +1486,7 @@ ol.Map.createOptionsInternal = function(options) {
       logos[logo] = '';
     } else if (logo instanceof HTMLElement) {
       logos[goog.getUid(logo).toString()] = logo;
-    } else if (goog.isObject(logo)) {
+    } else if (logo !== null) {
       goog.asserts.assertString(logo.href, 'logo.href should be a string');
       goog.asserts.assertString(logo.src, 'logo.src should be a string');
       logos[logo.src] = logo.href;
diff --git a/src/ol/renderer/layerrenderer.js b/src/ol/renderer/layerrenderer.js
index 4e24e83523..57f7383354 100644
--- a/src/ol/renderer/layerrenderer.js
+++ b/src/ol/renderer/layerrenderer.js
@@ -224,7 +224,7 @@ ol.renderer.Layer.prototype.updateLogos = function(frameState, source) {
   if (logo !== undefined) {
     if (typeof logo === 'string') {
       frameState.logos[logo] = '';
-    } else if (goog.isObject(logo)) {
+    } else if (logo !== null) {
       goog.asserts.assertString(logo.href, 'logo.href is a string');
       goog.asserts.assertString(logo.src, 'logo.src is a string');
       frameState.logos[logo.src] = logo.href;