diff --git a/java/client/src/org/openqa/selenium/firefox/internal/FileExtension.java b/java/client/src/org/openqa/selenium/firefox/internal/FileExtension.java
index 5adfaa138864a..228ceede27114 100644
--- a/java/client/src/org/openqa/selenium/firefox/internal/FileExtension.java
+++ b/java/client/src/org/openqa/selenium/firefox/internal/FileExtension.java
@@ -17,6 +17,8 @@
 
 package org.openqa.selenium.firefox.internal;
 
+import com.google.gson.JsonObject;
+import com.google.gson.JsonParser;
 import org.openqa.selenium.WebDriverException;
 import org.openqa.selenium.io.FileHandler;
 import org.openqa.selenium.io.TemporaryFilesystem;
@@ -30,6 +32,7 @@
 import java.io.FileNotFoundException;
 import java.io.IOException;
 import java.util.Iterator;
+import java.io.*;
 
 import javax.xml.XMLConstants;
 import javax.xml.namespace.NamespaceContext;
@@ -58,7 +61,7 @@ public void writeTo(File extensionsDir) throws IOException {
 
     File root = obtainRootDirectory(toInstall);
 
-    String id = readIdFromInstallRdf(root);
+    String id = getExtensionId(root);
 
     File extensionDirectory = new File(extensionsDir, id);
 
@@ -87,6 +90,46 @@ private File obtainRootDirectory(File extensionToInstall) throws IOException {
     return root;
   }
 
+  private String getExtensionId(File root) {
+    File manifestJson = new File(root, "manifest.json");
+    File installRdf = new File(root, "install.rdf");
+
+    if (installRdf.exists())
+      return readIdFromInstallRdf(root);
+    else if (manifestJson.exists())
+      return readIdFromManifestJson(root);
+    else
+      throw new WebDriverException(
+        "Extension should contain either install.rdf or manifest.json metadata file");
+
+  }
+
+  private String readIdFromManifestJson(File root) {
+    final String MANIFEST_JSON_FILE = "manifest.json";
+    File manifestJsonFile = new File(root, MANIFEST_JSON_FILE);
+    try {
+      String addOnId = null;
+      JsonObject manifestObject = new JsonParser().parse(new FileReader(manifestJsonFile)).getAsJsonObject();
+      if (manifestObject.has("applications")) {
+        JsonObject applicationObj = manifestObject.getAsJsonObject("applications");
+        if (applicationObj.has("gecko")) {
+          JsonObject geckoObj = applicationObj.getAsJsonObject("gecko");
+          if (geckoObj.has("id")) {
+            addOnId = geckoObj.get("id").getAsString().trim();
+          }
+        }
+      }
+
+      if (addOnId == null || addOnId.isEmpty()) {
+        addOnId = manifestObject.get("name").getAsString().replaceAll(" ", "") +
+          "@" + manifestObject.get("version").getAsString();
+      }
+
+      return addOnId;
+    } catch (FileNotFoundException e1) {
+      throw new WebDriverException("Unable to file manifest.json in xpi file");
+    }
+  }
 
   private String readIdFromInstallRdf(File root) {
     try {
diff --git a/java/client/test/org/openqa/selenium/firefox/FirefoxProfileTest.java b/java/client/test/org/openqa/selenium/firefox/FirefoxProfileTest.java
index 3411e8f1c670d..48d4e40cd2d3b 100644
--- a/java/client/test/org/openqa/selenium/firefox/FirefoxProfileTest.java
+++ b/java/client/test/org/openqa/selenium/firefox/FirefoxProfileTest.java
@@ -50,6 +50,7 @@ public class FirefoxProfileTest {
   private static final String FIREBUG_PATH = "third_party/firebug/firebug-1.5.0-fx.xpi";
   private static final String FIREBUG_RESOURCE_PATH =
       "/org/openqa/selenium/testing/drivers/firebug-1.5.0-fx.xpi";
+  private static final String MOOLTIPASS_PATH = "third_party/firebug/mooltipass-1.1.87.xpi";
 
   private FirefoxProfile profile;
 
@@ -159,6 +160,14 @@ public void shouldInstallExtensionFromZip() throws IOException {
     assertTrue(extensionDir.exists());
   }
 
+  @Test
+  public void shouldInstallWebExtensionFromZip() throws IOException {
+    profile.addExtension(InProject.locate(MOOLTIPASS_PATH).toFile());
+    File profileDir = profile.layoutOnDisk();
+    File extensionDir = new File(profileDir, "extensions/MooltipassExtension@1.1.87");
+    assertTrue(extensionDir.exists());
+  }
+
   @Test
   public void shouldInstallExtensionFromDirectory() throws IOException {
     File extension = InProject.locate(FIREBUG_PATH).toFile();
@@ -169,6 +178,16 @@ public void shouldInstallExtensionFromDirectory() throws IOException {
     assertTrue(extensionDir.exists());
   }
 
+  @Test
+  public void shouldInstallWebExtensionFromDirectory() throws IOException {
+    File extension = InProject.locate(MOOLTIPASS_PATH).toFile();
+    File unzippedExtension = Zip.unzipToTempDir(new FileInputStream(extension), "unzip", "stream");
+    profile.addExtension(unzippedExtension);
+    File profileDir = profile.layoutOnDisk();
+    File extensionDir = new File(profileDir, "extensions/MooltipassExtension@1.1.87");
+    assertTrue(extensionDir.exists());
+  }
+
   @Test
   public void shouldInstallExtensionUsingClasspath() throws IOException {
     profile.addExtension(Firebug.class, FIREBUG_RESOURCE_PATH);
diff --git a/third_party/firebug/mooltipass-1.1.87.xpi b/third_party/firebug/mooltipass-1.1.87.xpi
new file mode 100644
index 0000000000000..a2853a2245a46
Binary files /dev/null and b/third_party/firebug/mooltipass-1.1.87.xpi differ