diff --git a/src/Buffer.test.ts b/src/Buffer.test.ts
index 1ef2e92c66..a56fd63a4e 100644
--- a/src/Buffer.test.ts
+++ b/src/Buffer.test.ts
@@ -19,8 +19,8 @@ describe('Buffer', () => {
 
   beforeEach(() => {
     terminal = new MockTerminal();
-    terminal.cols = INIT_COLS;
-    terminal.rows = INIT_ROWS;
+    (terminal as any).cols = INIT_COLS;
+    (terminal as any).rows = INIT_ROWS;
     terminal.options.scrollback = 1000;
     buffer = new Buffer(terminal, true);
   });
diff --git a/src/BufferSet.test.ts b/src/BufferSet.test.ts
index 26f9cd42f7..576a8ca472 100644
--- a/src/BufferSet.test.ts
+++ b/src/BufferSet.test.ts
@@ -15,8 +15,8 @@ describe('BufferSet', () => {
 
   beforeEach(() => {
     terminal = new MockTerminal();
-    terminal.cols = 80;
-    terminal.rows = 24;
+    (terminal as any).cols = 80;
+    (terminal as any).rows = 24;
     terminal.options.scrollback = 1000;
     bufferSet = new BufferSet(terminal);
   });
diff --git a/src/Linkifier.test.ts b/src/Linkifier.test.ts
index 0ba1294a0e..07dbf1b3b0 100644
--- a/src/Linkifier.test.ts
+++ b/src/Linkifier.test.ts
@@ -41,8 +41,8 @@ describe('Linkifier', () => {
 
   beforeEach(() => {
     terminal = new MockTerminal();
-    terminal.cols = 100;
-    terminal.rows = 10;
+    (terminal as any).cols = 100;
+    (terminal as any).rows = 10;
     terminal.buffer = new MockBuffer();
     (<MockBuffer>terminal.buffer).setLines(new CircularList<IBufferLine>(20));
     terminal.buffer.ydisp = 0;
@@ -65,7 +65,7 @@ describe('Linkifier', () => {
   function assertLinkifiesRow(rowText: string, linkMatcherRegex: RegExp, links: {x: number, length: number}[], done: MochaDone): void {
     addRow(rowText);
     linkifier.registerLinkMatcher(linkMatcherRegex, () => {});
-    terminal.rows = terminal.buffer.lines.length - 1;
+    (terminal as any).rows = terminal.buffer.lines.length - 1;
     linkifier.linkifyRows();
     // Allow linkify to happen
     setTimeout(() => {
@@ -142,19 +142,19 @@ describe('Linkifier', () => {
       });
       describe('multi-line links', () => {
         it('should match links that start on line 1/2 of a wrapped line and end on the last character of line 1/2', done => {
-          terminal.cols = 4;
+          (terminal as any).cols = 4;
           assertLinkifiesMultiLineLink('12345', /1234/, [{x1: 0, x2: 4, y1: 0, y2: 0}], done);
         });
         it('should match links that start on line 1/2 of a wrapped line and wrap to line 2/2', done => {
-          terminal.cols = 4;
+          (terminal as any).cols = 4;
           assertLinkifiesMultiLineLink('12345', /12345/, [{x1: 0, x2: 1, y1: 0, y2: 1}], done);
         });
         it('should match links that start and end on line 2/2 of a wrapped line', done => {
-          terminal.cols = 4;
+          (terminal as any).cols = 4;
           assertLinkifiesMultiLineLink('12345678', /5678/, [{x1: 0, x2: 4, y1: 1, y2: 1}], done);
         });
         it('should match links that start on line 2/3 of a wrapped line and wrap to line 3/3', done => {
-          terminal.cols = 4;
+          (terminal as any).cols = 4;
           assertLinkifiesMultiLineLink('123456789', /56789/, [{x1: 0, x2: 1, y1: 1, y2: 2}], done);
         });
       });
diff --git a/src/SelectionManager.test.ts b/src/SelectionManager.test.ts
index 2f74ccdab0..21bc6754b2 100644
--- a/src/SelectionManager.test.ts
+++ b/src/SelectionManager.test.ts
@@ -45,8 +45,8 @@ describe('SelectionManager', () => {
 
   beforeEach(() => {
     terminal = new TestMockTerminal();
-    terminal.cols = 80;
-    terminal.rows = 2;
+    (terminal as any).cols = 80;
+    (terminal as any).rows = 2;
     terminal.options.scrollback = 100;
     terminal.buffers = new BufferSet(terminal);
     terminal.buffer = terminal.buffers.active;
diff --git a/src/SelectionModel.test.ts b/src/SelectionModel.test.ts
index 8d4b30bb58..d49f41d0c7 100644
--- a/src/SelectionModel.test.ts
+++ b/src/SelectionModel.test.ts
@@ -23,8 +23,8 @@ describe('SelectionManager', () => {
 
   beforeEach(() => {
     terminal = new MockTerminal();
-    terminal.cols = 80;
-    terminal.rows = 2;
+    (terminal as any).cols = 80;
+    (terminal as any).rows = 2;
     terminal.options.scrollback = 10;
     terminal.buffers = new BufferSet(terminal);
     terminal.buffer = terminal.buffers.active;
diff --git a/src/Types.ts b/src/Types.ts
index aac029f215..31e423391c 100644
--- a/src/Types.ts
+++ b/src/Types.ts
@@ -237,7 +237,7 @@ export interface IBufferAccessor {
 }
 
 export interface IElementAccessor {
-  element: HTMLElement;
+  readonly element: HTMLElement;
 }
 
 export interface ILinkifierAccessor {
diff --git a/typings/xterm.d.ts b/typings/xterm.d.ts
index 11fab9097e..dc9ebbae43 100644
--- a/typings/xterm.d.ts
+++ b/typings/xterm.d.ts
@@ -314,28 +314,32 @@ declare module 'xterm' {
     /**
      * The element containing the terminal.
      */
-    element: HTMLElement;
+    readonly element: HTMLElement;
 
     /**
      * The textarea that accepts input for the terminal.
      */
-    textarea: HTMLTextAreaElement;
+    readonly textarea: HTMLTextAreaElement;
 
     /**
-     * The number of rows in the terminal's viewport.
+     * The number of rows in the terminal's viewport. Use
+     * `ITerminalOptions.rows` to set this in the constructor and
+     * `Terminal.resize` for when the terminal exists.
      */
-    rows: number;
+    readonly rows: number;
 
     /**
-     * The number of columns in the terminal's viewport.
+     * The number of columns in the terminal's viewport. Use
+     * `ITerminalOptions.cols` to set this in the constructor and
+     * `Terminal.resize` for when the terminal exists.
      */
-    cols: number;
+    readonly cols: number;
 
     /**
      * (EXPERIMENTAL) Get all markers registered against the buffer. If the alt
      * buffer is active this will always return [].
      */
-    markers: IMarker[];
+    readonly markers: IMarker[];
 
     /**
      * Natural language strings that can be localized.