diff --git a/Makefile b/Makefile
index e99daa832..107551d6a 100644
--- a/Makefile
+++ b/Makefile
@@ -5,7 +5,9 @@ DEFAULT_BROWSERS := resources/browser_manifests/browser_manifest.json
 DEFAULT_TESTS := test_manifest.json
 
 EXTENSION_SRC := ./extensions/
+EXTENSION_BASE_VERSION := 4bb289ec499013de66eb421737a4dbb4a9273eda
 FIREFOX_EXTENSION_NAME := pdf.js.xpi
+FIREFOX_AMO_EXTENSION_NAME := pdf.js.amo.xpi
 CHROME_EXTENSION_NAME := pdf.js.crx
 
 all: bundle
@@ -158,7 +160,7 @@ web: | production extension compiler pages-repo
 	@cp $(BUILD_TARGET) $(GH_PAGES)/$(BUILD_TARGET)
 	@cp -R web/* $(GH_PAGES)/web
 	@cp web/images/* $(GH_PAGES)/web/images
-	@cp $(EXTENSION_SRC)/firefox/*.xpi $(GH_PAGES)/$(EXTENSION_SRC)/firefox/
+	@cp $(FIREFOX_BUILD_DIR)/$(FIREFOX_EXTENSION_NAME) $(FIREFOX_BUILD_DIR)/update.rdf $(GH_PAGES)/$(EXTENSION_SRC)/firefox/
 	@cp $(GH_PAGES)/web/index.html.template $(GH_PAGES)/index.html;
 	@mv -f $(GH_PAGES)/web/viewer-production.html $(GH_PAGES)/web/viewer.html;
 	@cd $(GH_PAGES); git add -A;
@@ -201,8 +203,7 @@ pages-repo: | $(BUILD_DIR)
 # This target produce a restartless firefox extension containing a
 # copy of the pdf.js source.
 CONTENT_DIR := content
-FIREFOX_CONTENT_DIR := $(EXTENSION_SRC)/firefox/$(CONTENT_DIR)/
-CHROME_CONTENT_DIR := $(EXTENSION_SRC)/chrome/$(CONTENT_DIR)/
+BUILD_NUMBER := `git log --format=oneline $(EXTENSION_BASE_VERSION).. | wc -l | awk '{print $$1}'`
 PDF_WEB_FILES = \
 	web/images \
 	web/compatibility.js \
@@ -210,26 +211,66 @@ PDF_WEB_FILES = \
 	web/viewer.js \
 	web/viewer-production.html \
 	$(NULL)
+
+FIREFOX_BUILD_DIR := $(BUILD_DIR)/firefox
+FIREFOX_BUILD_CONTENT := $(FIREFOX_BUILD_DIR)/$(CONTENT_DIR)/
+FIREFOX_CONTENT_DIR := $(EXTENSION_SRC)/firefox/$(CONTENT_DIR)/
+FIREFOX_EXTENSION_FILES_TO_COPY = \
+	*.js \
+	*.rdf \
+	chrome.manifest \
+	components \
+	$(NULL)
+FIREFOX_EXTENSION_FILES = \
+	content \
+	*.js \
+	install.rdf \
+	chrome.manifest \
+	components \
+	content \
+	$(NULL)
+
+CHROME_BUILD_DIR := $(BUILD_DIR)/chrome
+CHROME_CONTENT_DIR := $(EXTENSION_SRC)/chrome/$(CONTENT_DIR)/
+CHROME_BUILD_CONTENT := $(CHROME_BUILD_DIR)/$(CONTENT_DIR)/
+CHROME_EXTENSION_FILES = \
+	extensions/chrome/*.json \
+	extensions/chrome/*.html \
+	$(NULL)
 extension: | production
+	# Clear out everything in the firefox extension build directory
+	@rm -Rf $(FIREFOX_BUILD_DIR)
+	@mkdir -p $(FIREFOX_BUILD_CONTENT)
+	@mkdir -p $(FIREFOX_BUILD_CONTENT)/$(BUILD_DIR)
+	@mkdir -p $(FIREFOX_BUILD_CONTENT)/web
+	@cd extensions/firefox; cp -r $(FIREFOX_EXTENSION_FILES_TO_COPY) ../../$(FIREFOX_BUILD_DIR)/
 	# Copy a standalone version of pdf.js inside the content directory
-	@rm -Rf $(FIREFOX_CONTENT_DIR)
-	@mkdir -p $(FIREFOX_CONTENT_DIR)/$(BUILD_DIR)
-	@mkdir -p $(FIREFOX_CONTENT_DIR)/web
-	@cp $(BUILD_TARGET) $(FIREFOX_CONTENT_DIR)/$(BUILD_DIR)
-	@cp -r $(PDF_WEB_FILES) $(FIREFOX_CONTENT_DIR)/web/
-	@mv -f $(FIREFOX_CONTENT_DIR)/web/viewer-production.html $(FIREFOX_CONTENT_DIR)/web/viewer.html
-
+	@cp $(BUILD_TARGET) $(FIREFOX_BUILD_CONTENT)/$(BUILD_DIR)/
+	@cp -r $(PDF_WEB_FILES) $(FIREFOX_BUILD_CONTENT)/web/
+	@mv -f $(FIREFOX_BUILD_CONTENT)/web/viewer-production.html $(FIREFOX_BUILD_CONTENT)/web/viewer.html
+	# Update the build version number
+	@sed -i.bak "s/PDFJSSCRIPT_BUILD/$(BUILD_NUMBER)/" $(FIREFOX_BUILD_DIR)/install.rdf
+	@sed -i.bak "s/PDFJSSCRIPT_BUILD/$(BUILD_NUMBER)/" $(FIREFOX_BUILD_DIR)/update.rdf
+	@rm -f $(FIREFOX_BUILD_DIR)/*.bak
 	# Create the xpi
-	@cd $(EXTENSION_SRC)/firefox; zip -r $(FIREFOX_EXTENSION_NAME) *
+	@cd $(FIREFOX_BUILD_DIR); zip -r $(FIREFOX_EXTENSION_NAME) $(FIREFOX_EXTENSION_FILES)
 	@echo "extension created: " $(FIREFOX_EXTENSION_NAME)
+	# Build the amo extension too (remove the updateUrl)
+	@sed -i.bak "/updateURL/d" $(FIREFOX_BUILD_DIR)/install.rdf
+	@rm -f $(FIREFOX_BUILD_DIR)/*.bak
+	@cd $(FIREFOX_BUILD_DIR); zip -r $(FIREFOX_AMO_EXTENSION_NAME) $(FIREFOX_EXTENSION_FILES)
+	@echo "AMO extension created: " $(FIREFOX_AMO_EXTENSION_NAME)
 
-  # Copy a standalone version of pdf.js inside the extension directory
-	@rm -Rf $(CHROME_CONTENT_DIR)
-	@mkdir -p $(CHROME_CONTENT_DIR)/$(BUILD_DIR)
-	@mkdir -p $(CHROME_CONTENT_DIR)/web
-	@cp $(BUILD_TARGET) $(CHROME_CONTENT_DIR)/$(BUILD_DIR)
-	@cp -r $(PDF_WEB_FILES) $(CHROME_CONTENT_DIR)/web/
-	@mv -f $(CHROME_CONTENT_DIR)/web/viewer-production.html $(CHROME_CONTENT_DIR)/web/viewer.html
+	# Clear out everything in the chrome extension build directory
+	@rm -Rf $(CHROME_BUILD_DIR)
+	@mkdir -p $(CHROME_BUILD_CONTENT)
+	@mkdir -p $(CHROME_BUILD_CONTENT)/$(BUILD_DIR)
+	@mkdir -p $(CHROME_BUILD_CONTENT)/web
+	@cp -R $(CHROME_EXTENSION_FILES) $(CHROME_BUILD_DIR)/
+	# Copy a standalone version of pdf.js inside the content directory
+	@cp $(BUILD_TARGET) $(CHROME_BUILD_CONTENT)/$(BUILD_DIR)/
+	@cp -r $(PDF_WEB_FILES) $(CHROME_BUILD_CONTENT)/web/
+	@mv -f $(CHROME_BUILD_CONTENT)/web/viewer-production.html $(CHROME_BUILD_CONTENT)/web/viewer.html
 
   # Create the crx
   #TODO
diff --git a/extensions/firefox/install.rdf b/extensions/firefox/install.rdf
index 8b793c525..f4e6b43ea 100644
--- a/extensions/firefox/install.rdf
+++ b/extensions/firefox/install.rdf
@@ -6,7 +6,7 @@
   <Description about="urn:mozilla:install-manifest">
     <em:id>uriloader@pdf.js</em:id>
     <em:name>pdf.js</em:name>
-    <em:version>0.1.0</em:version>
+    <em:version>0.2.PDFJSSCRIPT_BUILD</em:version>
 	  <em:iconURL>chrome://pdf.js/skin/logo.png</em:iconURL>
     <em:targetApplication>
       <Description>
@@ -17,9 +17,11 @@
     </em:targetApplication>
     <em:bootstrap>true</em:bootstrap>
     <em:unpack>true</em:unpack>
-    <em:creator>Vivien Nicolas</em:creator>
+    <em:creator>Mozilla Labs</em:creator>
     <em:description>pdf.js uri loader</em:description>
     <em:homepageURL>https://github.com/mozilla/pdf.js/</em:homepageURL>
     <em:type>2</em:type>
+    <!-- Use the raw link for updates so we we can use SSL. -->
+    <em:updateURL>https://github.com/mozilla/pdf.js/raw/gh-pages/extensions/firefox/update.rdf</em:updateURL>
   </Description>
 </RDF>
diff --git a/extensions/firefox/update.rdf b/extensions/firefox/update.rdf
new file mode 100644
index 000000000..c12e53dc6
--- /dev/null
+++ b/extensions/firefox/update.rdf
@@ -0,0 +1,26 @@
+<?xml version="1.0" encoding="UTF-8"?>
+
+<RDF:RDF xmlns:RDF="http://www.w3.org/1999/02/22-rdf-syntax-ns#"
+         xmlns:em="http://www.mozilla.org/2004/em-rdf#">
+
+  <RDF:Description about="urn:mozilla:extension:uriloader@pdf.js">
+    <em:updates>
+      <RDF:Seq>
+        <RDF:li>
+          <RDF:Description>
+            <em:version>0.2.PDFJSSCRIPT_BUILD</em:version>
+            <em:targetApplication>
+              <RDF:Description>
+                <em:id>{ec8030f7-c20a-464f-9b0e-13a3a9e97384}</em:id>
+                <em:minVersion>6.0</em:minVersion>
+                <em:maxVersion>11.*</em:maxVersion>
+                <!-- Use the raw link for updates so we we can use SSL. -->
+                <em:updateLink>https://github.com/mozilla/pdf.js/raw/gh-pages/extensions/firefox/pdf.js.xpi</em:updateLink>
+              </RDF:Description>
+            </em:targetApplication>
+          </RDF:Description>
+        </RDF:li>
+      </RDF:Seq>
+    </em:updates>
+  </RDF:Description>
+</RDF:RDF>
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