diff --git a/src/compiler/factory.ts b/src/compiler/factory.ts
index 56d132fc925b4..507997c346de3 100644
--- a/src/compiler/factory.ts
+++ b/src/compiler/factory.ts
@@ -24,14 +24,14 @@ namespace ts {
      * Make `elements` into a `NodeArray<T>`. If `elements` is `undefined`, returns an empty `NodeArray<T>`.
      */
     export function createNodeArray<T extends Node>(elements?: ReadonlyArray<T>, hasTrailingComma?: boolean): NodeArray<T> {
-        if (elements) {
+        if (!elements || elements === emptyArray) {
+            elements = [];
+        }
+        else {
             if (isNodeArray(elements)) {
                 return elements;
             }
         }
-        else {
-            elements = [];
-        }
 
         const array = <NodeArray<T>>elements;
         array.pos = -1;
diff --git a/src/harness/unittests/tscWatchMode.ts b/src/harness/unittests/tscWatchMode.ts
index 278127e81cea4..47116cd5b0129 100644
--- a/src/harness/unittests/tscWatchMode.ts
+++ b/src/harness/unittests/tscWatchMode.ts
@@ -2333,9 +2333,9 @@ declare module "fs" {
                 verifyRenamingFileInSubFolder(TestFSWithWatch.Tsc_WatchDirectory.NonRecursiveWatchDirectory);
             });
 
-            // it("uses non recursive dynamic polling when renaming file in subfolder", () => {
-            //     verifyRenamingFileInSubFolder(TestFSWithWatch.Tsc_WatchDirectory.DynamicPolling);
-            // });
+            it("uses non recursive dynamic polling when renaming file in subfolder", () => {
+                verifyRenamingFileInSubFolder(TestFSWithWatch.Tsc_WatchDirectory.DynamicPolling);
+            });
         });
     });
 }
diff --git a/src/harness/virtualFileSystemWithWatch.ts b/src/harness/virtualFileSystemWithWatch.ts
index dd2f123826018..9c8744f179e41 100644
--- a/src/harness/virtualFileSystemWithWatch.ts
+++ b/src/harness/virtualFileSystemWithWatch.ts
@@ -88,7 +88,7 @@ interface Array<T> {}`
     }
 
     interface Folder extends FSEntry {
-        entries: FSEntry[];
+        entries: SortedArray<FSEntry>;
     }
 
     interface SymLink extends FSEntry {
@@ -504,7 +504,7 @@ interface Array<T> {}`
         }
 
         private addFileOrFolderInFolder(folder: Folder, fileOrDirectory: File | Folder | SymLink, ignoreWatch?: boolean) {
-            folder.entries.push(fileOrDirectory);
+            insertSorted(folder.entries, fileOrDirectory, (a, b) => compareStringsCaseSensitive(getBaseFileName(a.path), getBaseFileName(b.path)));
             folder.modifiedTime = new Date();
             this.fs.set(fileOrDirectory.path, fileOrDirectory);
 
@@ -606,7 +606,7 @@ interface Array<T> {}`
 
         private toFolder(path: string): Folder {
             const folder = this.toFsEntry(path) as Folder;
-            folder.entries = [];
+            folder.entries = [] as SortedArray<FSEntry>;
             return folder;
         }