diff --git a/src/tilesource.js b/src/tilesource.js
index 135053de..431b37d3 100644
--- a/src/tilesource.js
+++ b/src/tilesource.js
@@ -629,7 +629,11 @@ function processResponse( xhr ){
             data = xhr.responseText;
         }
     }else if( responseText.match(/\s*[\{\[].*/) ){
-        data = $.parseJSON(responseText);
+        try{
+          data = $.parseJSON(responseText);
+        } catch(e){
+          data =  responseText;
+        }
     }else{
         data = responseText;
     }
diff --git a/src/viewer.js b/src/viewer.js
index f59bf8a7..91317cd3 100644
--- a/src/viewer.js
+++ b/src/viewer.js
@@ -2114,19 +2114,6 @@ function _getSafeElemSize (oElement) {
 }
 
 
-/*
- * @function
- * @private
- */
-function _isJSON(str){
-  try{
-    JSON.parse(str);
-  } catch (e) {
-    return false;
-  }
-  return true;
-}
-
 /**
  * @function
  * @private
@@ -2141,8 +2128,13 @@ function getTileSourceImplementation( viewer, tileSource, imgOptions, successCal
         if ( tileSource.match( /^\s*<.*>\s*$/ ) ) {
             tileSource = $.parseXml( tileSource );
         //json should start with "{" or "[" and end with "}" or "]"
-        } else if ( _isJSON(tileSource) ) {
-            tileSource = $.parseJSON(tileSource);
+        } else if ( tileSource.match(/^\s*[\{\[].*[\}\]]\s*$/ ) ) {
+            try {
+              var tileSourceJ = $.parseJSON(tileSource);
+              tileSource = tileSourceJ;
+            } catch (e) {
+              //tileSource = tileSource;
+            }
         }
     }