diff --git a/lib/Browser.js b/lib/Browser.js
index 25654687aee..b2166ff3532 100644
--- a/lib/Browser.js
+++ b/lib/Browser.js
@@ -61,6 +61,7 @@ class Browser {
         }
         if (Array.isArray(options.args))
             this._chromeArguments.push(...options.args);
+        this._terminated = false;
         this._chromeProcess = null;
         this._tabSymbol = Symbol('Browser.TabSymbol');
     }
@@ -70,7 +71,7 @@ class Browser {
      */
     async newPage() {
         await this._ensureChromeIsRunning();
-        if (!this._chromeProcess || this._chromeProcess.killed)
+        if (!this._chromeProcess || this._terminated)
             throw new Error('ERROR: this chrome instance is not alive any more!');
         var tab = await CDP.New({port: this._remoteDebuggingPort});
         var client = await CDP({tab: tab, port: this._remoteDebuggingPort});
@@ -83,7 +84,7 @@ class Browser {
      * @param {!Page} page
      */
     async closePage(page) {
-        if (!this._chromeProcess || this._chromeProcess.killed)
+        if (!this._chromeProcess || this._terminated)
             throw new Error('ERROR: this chrome instance is not running');
         var tab = page[this._tabSymbol];
         if (!tab)
@@ -106,7 +107,10 @@ class Browser {
         this._chromeProcess = childProcess.spawn(this._chromeExecutable, this._chromeArguments, {});
         // Cleanup as processes exit.
         process.on('exit', () => this._chromeProcess.kill());
-        this._chromeProcess.on('exit', () => removeRecursive(this._userDataDir));
+        this._chromeProcess.on('exit', () => {
+            this._terminated = true;
+            removeRecursive(this._userDataDir);
+        });
 
         await waitForChromeResponsive(this._remoteDebuggingPort);
     }
diff --git a/lib/Page.js b/lib/Page.js
index e3a08e20416..30ca2b2a610 100644
--- a/lib/Page.js
+++ b/lib/Page.js
@@ -314,7 +314,7 @@ class Page extends EventEmitter {
     /**
      * @param {function()} fun
      * @param {!Array<*>} args
-     * @return {!Promise<(!Object|udndefined)>}
+     * @return {!Promise<(!Object|undefined)>}
      */
     async evaluate(fun, ...args) {
         var response = await helpers.evaluate(this._client, fun, args, false /* awaitPromise */);
@@ -328,7 +328,7 @@ class Page extends EventEmitter {
     /**
      * @param {function()} fun
      * @param {!Array<*>} args
-     * @return {!Promise<(!Object|udndefined)>}
+     * @return {!Promise<(!Object|undefined)>}
      */
     async evaluateAsync(fun, ...args) {
         var response = await helpers.evaluate(this._client, fun, args, true /* awaitPromise */);
@@ -396,7 +396,7 @@ class Page extends EventEmitter {
         else if (mimeType === 'image/jpeg')
             screenshotType = Page.ScreenshotTypes.JPG;
         if (!screenshotType)
-            throw new Error(`Cannot render to file ${fileName} - unsupported mimeType ${mimeType}`);
+            throw new Error(`Cannot render to file ${filePath} - unsupported mimeType ${mimeType}`);
         var buffer = await this.screenshot(screenshotType, clipRect);
         fs.writeFileSync(filePath, buffer);
     }
@@ -538,7 +538,7 @@ function convertPrintParameterToInches(parameter) {
         }
         var value = Number(valueText);
         console.assert(!isNaN(value), 'Failed to parse parameter value: ' + text);
-        var pixels = value * unitToPixels[unit];
+        pixels = value * unitToPixels[unit];
     } else {
         throw new Error('printToPDF Cannot handle parameter type: ' + (typeof parameter));
     }