diff --git a/build.sh b/build.sh
index 3ae4f29..e153a8b 100755
--- a/build.sh
+++ b/build.sh
@@ -6,6 +6,7 @@
 
 # This script assumes the following directory structure:
 # ./
+#   manifest.json (optional - for even newer extensions)
 #   chrome.manifest (optional - for newer extensions)
 #   install.rdf
 #   (other files listed in $ROOT_FILES)
@@ -85,7 +86,7 @@ for DIR in $ROOT_DIRS; do
 done
 
 # Copy other files to the root of future XPI.
-for ROOT_FILE in $ROOT_FILES install.rdf chrome.manifest; do
+for ROOT_FILE in $ROOT_FILES install.rdf chrome.manifest manifest.json; do
   cp --verbose $ROOT_FILE $TMP_DIR
   if [ -f $ROOT_FILE ]; then
     echo $ROOT_FILE >> files
diff --git a/content/icon23x32.png b/content/icon23x32.png
new file mode 100644
index 0000000..2243659
Binary files /dev/null and b/content/icon23x32.png differ
diff --git a/manifest.json b/manifest.json
new file mode 100644
index 0000000..e0a5cee
--- /dev/null
+++ b/manifest.json
@@ -0,0 +1,22 @@
+{
+    "manifest_version": 2,
+    "applications": {
+      "gecko": {
+        "id": "tbdialout@oak-wood.co.uk",
+        "strict_min_version": "68.0"
+      }
+    },
+    "name": "TBDialOut",
+    "description": "Place phone calls directly from Thunderbird's address book",
+    "version": "1.7.4",
+    "icons": {
+      "32": "content/icon32x32.png"
+    },
+    "legacy": {
+      "type": "xul",
+      "options": {
+        "page": "chrome://tbdialout/content/options.xul",
+        "open_in_tab": true
+      }
+    }
+  }
\ No newline at end of file