diff --git a/lib/ace/edit_session.js b/lib/ace/edit_session.js
index 260baa5e..874ac938 100644
--- a/lib/ace/edit_session.js
+++ b/lib/ace/edit_session.js
@@ -2187,7 +2187,7 @@ var EditSession = function(text, mode) {
 
         while (row <= screenRow) {
             rowLength = this.getRowLength(docRow);
-            if (row + rowLength - 1 >= screenRow || docRow >= maxRow) {
+            if (row + rowLength > screenRow || docRow >= maxRow) {
                 break;
             } else {
                 row += rowLength;
@@ -2222,9 +2222,10 @@ var EditSession = function(text, mode) {
         if (this.$useWrapMode) {
             var splits = this.$wrapData[docRow];
             if (splits) {
-                column = splits[screenRow - row];
-                if(screenRow > row && splits.length) {
-                    docColumn = splits[screenRow - row - 1] || splits[splits.length - 1];
+                var splitIndex = Math.floor(screenRow - row);
+                column = splits[splitIndex];
+                if(splitIndex > 0 && splits.length) {
+                    docColumn = splits[splitIndex - 1] || splits[splits.length - 1];
                     line = line.substring(docColumn);
                 }
             }
diff --git a/lib/ace/edit_session/folding.js b/lib/ace/edit_session/folding.js
index a9b2ddd1..b5bc36bd 100644
--- a/lib/ace/edit_session/folding.js
+++ b/lib/ace/edit_session/folding.js
@@ -627,6 +627,8 @@ function Folding() {
         if (depth == undefined)
             depth = 100000; // JSON.stringify doesn't hanle Infinity
         var foldWidgets = this.foldWidgets;
+        if (!foldWidgets)
+            return; // mode doesn't support folding
         endRow = endRow || this.getLength();
         startRow = startRow || 0;
         for (var row = startRow; row < endRow; row++) {