diff --git a/extensions/git-extended/src/common/models/diffHunk.ts b/extensions/git-extended/src/common/models/diffHunk.ts
new file mode 100644
index 00000000000..cf553ee2e3a
--- /dev/null
+++ b/extensions/git-extended/src/common/models/diffHunk.ts
@@ -0,0 +1,16 @@
+/*---------------------------------------------------------------------------------------------
+ *  Copyright (c) Microsoft Corporation. All rights reserved.
+ *  Licensed under the MIT License. See License.txt in the project root for license information.
+ *--------------------------------------------------------------------------------------------*/
+
+import { DiffLine } from './diffLine';
+
+export class DiffHunk {
+	public Lines: DiffLine[] = [];
+
+	constructor(
+		public oldLineNumber: number,
+		public newLineNumber: number,
+		public diffLine: number
+	) { }
+}
\ No newline at end of file
diff --git a/extensions/git-extended/src/common/models/diffLine.ts b/extensions/git-extended/src/common/models/diffLine.ts
new file mode 100644
index 00000000000..6a14a19c4b8
--- /dev/null
+++ b/extensions/git-extended/src/common/models/diffLine.ts
@@ -0,0 +1,46 @@
+/*---------------------------------------------------------------------------------------------
+ *  Copyright (c) Microsoft Corporation. All rights reserved.
+ *  Licensed under the MIT License. See License.txt in the project root for license information.
+ *--------------------------------------------------------------------------------------------*/
+
+export enum DiffChangeType {
+	None,
+	Add,
+	Delete,
+	Control
+}
+
+export class DiffLine {
+	// Was the line added, deleted or unchanged.
+	type: DiffChangeType;
+
+	// Gets the old 1-based line number.
+	oldLineNumber: number = -1;
+
+	// Gets the new 1-based line number.
+	newLineNumber: number = -1;
+
+	// Gets the unified diff line number where the first chunk header is line 0.
+	diffLineNumber: number = -1;
+
+	// Gets the content of the diff line (including +, - or space).
+	content: String;
+
+	constructor(type: DiffChangeType, oldLineNumber: number, newLineNumber: number, diffLineNumber: number, content: string) {
+		this.type = type;
+		this.oldLineNumber = oldLineNumber;
+		this.newLineNumber = newLineNumber;
+		this.diffLineNumber = diffLineNumber;
+		this.content = content;
+	}
+}
+
+export function getDiffChangeType(text: string) {
+	let c = text[0];
+	switch (c) {
+		case ' ': return DiffChangeType.None;
+		case '+': return DiffChangeType.Add;
+		case '-': return DiffChangeType.Delete;
+		case '\\': return DiffChangeType.Control;
+	}
+}
\ No newline at end of file
diff --git a/extensions/git-extended/src/prView/prProvider.ts b/extensions/git-extended/src/prView/prProvider.ts
index 438c44c9639..6e99cb1e9bd 100644
--- a/extensions/git-extended/src/prView/prProvider.ts
+++ b/extensions/git-extended/src/prView/prProvider.ts
@@ -169,6 +169,9 @@ export class PRProvider implements vscode.TreeDataProvider<PRGroupTreeItem | Pul
 					if (document.uri.scheme === 'pr') {
 						let params = JSON.parse(document.uri.query);
 						let fileChange = richContentChanges.find(change => change.fileName === params.fileName);
+						if (!fileChange) {
+							return null;
+						}
 						let regex = new RegExp(DIFF_HUNK_INFO, 'g');
 						let matches = regex.exec(fileChange.patch);
 
@@ -229,6 +232,7 @@ export class PRProvider implements vscode.TreeDataProvider<PRGroupTreeItem | Pul
 						return {
 							threads,
 							commentingRanges,
+							collapsibleState: vscode.CommentThreadCollapsibleState.Expanded,
 							reply: reply
 						};
 
diff --git a/src/vs/workbench/api/electron-browser/mainThreadComments.ts b/src/vs/workbench/api/electron-browser/mainThreadComments.ts
index 7a4e438f8cb..9a69533138a 100644
--- a/src/vs/workbench/api/electron-browser/mainThreadComments.ts
+++ b/src/vs/workbench/api/electron-browser/mainThreadComments.ts
@@ -54,7 +54,7 @@ export class MainThreadComments extends Disposable implements MainThreadComments
 
 			const outerEditorURI = outerEditor.getModel().uri;
 			this.provideDocumentComments(outerEditorURI).then(commentInfos => {
-				this._commentService.setComments(outerEditorURI, commentInfos);
+				this._commentService.setComments(outerEditorURI, commentInfos.filter(info => info !== null));
 			});
 
 			for (const handle of keys(this._documentProviders)) {
diff --git a/src/vs/workbench/api/node/extHostComments.ts b/src/vs/workbench/api/node/extHostComments.ts
index 6d1af9226f5..ba069be736f 100644
--- a/src/vs/workbench/api/node/extHostComments.ts
+++ b/src/vs/workbench/api/node/extHostComments.ts
@@ -73,7 +73,7 @@ export class ExtHostComments implements ExtHostCommentsShape {
 			let provider = this._documentProviders.get(handle);
 			return provider.provideDocumentComments(data.document, token);
 		})
-			.then(commentInfo => convertCommentInfo(handle, commentInfo, this._commandsConverter));
+			.then(commentInfo => commentInfo ? convertCommentInfo(handle, commentInfo, this._commandsConverter) : null);
 	}
 
 	$provideWorkspaceComments(handle: number): TPromise<modes.CommentThread[]> {