diff --git a/includes/fbproduct.php b/includes/fbproduct.php
index 12a3b41b5..3eabf797e 100644
--- a/includes/fbproduct.php
+++ b/includes/fbproduct.php
@@ -896,6 +896,10 @@ public function prepare_product( $retailer_id = null, $type_to_prepare_for = sel
 			$product_data['gtin'] = $gtin;
 		}
 
+		if ( $date_modified = $this->woo_product->get_date_modified() ) {
+			$product_data[ 'external_update_time' ] = $date_modified->getTimestamp();
+		}
+
 		// Only use checkout URLs if they exist.
 		$checkout_url = $this->build_checkout_url( $product_url );
 		if ( $checkout_url ) {
diff --git a/includes/fbproductfeed.php b/includes/fbproductfeed.php
index d65ed4192..6911371ba 100644
--- a/includes/fbproductfeed.php
+++ b/includes/fbproductfeed.php
@@ -384,7 +384,7 @@ public function get_product_feed_header_row() {
 		return 'id,title,description,image_link,link,product_type,' .
 		'brand,price,availability,item_group_id,checkout_url,' .
 		'additional_image_link,sale_price_effective_date,sale_price,condition,' .
-		'visibility,gender,color,size,pattern,google_product_category,default_product,variant,gtin,quantity_to_sell_on_facebook,rich_text_description' . PHP_EOL;
+		'visibility,gender,color,size,pattern,google_product_category,default_product,variant,gtin,quantity_to_sell_on_facebook,rich_text_description,external_update_time' . PHP_EOL;
 	}
 
 
@@ -533,7 +533,8 @@ private function prepare_product_for_feed( $woo_product, &$attribute_variants )
 		static::format_string_for_feed( static::get_value_from_product_data( $product_data, 'variant' )) . ',' .
 		static::format_string_for_feed( static::get_value_from_product_data( $product_data, 'gtin' )) . ',' .
 		static::format_string_for_feed( static::get_value_from_product_data( $product_data, 'quantity_to_sell_on_facebook' )) . ',' .
-		static::format_string_for_feed( static::get_value_from_product_data( $product_data, 'rich_text_description' ) ) . PHP_EOL;
+		static::format_string_for_feed( static::get_value_from_product_data( $product_data, 'rich_text_description' ) ) . ',' .
+		static::get_value_from_product_data( $product_data, 'external_update_time' ) . PHP_EOL;
 	}
 
 	private static function format_additional_image_url( $product_image_urls ) {
diff --git a/tests/Unit/fbproductTest.php b/tests/Unit/fbproductTest.php
index c6bbe7396..a6506ba33 100644
--- a/tests/Unit/fbproductTest.php
+++ b/tests/Unit/fbproductTest.php
@@ -865,4 +865,34 @@ public function test_get_fb_brand_variable_products() {
 		$brand = $facebook_product_variation->get_fb_brand();
 		$this->assertEquals($brand, 'Adidas');
 	}
+
+	/**
+	 * Test external_update_time is populated
+	 * @return void
+	 */
+	public function test_external_update_time_set() {
+		$woo_product = WC_Helper_Product::create_simple_product();
+
+		$timestamp = time();
+		$woo_product->set_date_modified($timestamp);
+
+		$fb_product = new \WC_Facebook_Product( $woo_product );
+		$data = $fb_product->prepare_product();
+
+		$this->assertEquals( $data['external_update_time'], $timestamp);
+	}
+
+	/**
+	 * Test external_update_time is not populated
+	 * @return void
+	 */
+	public function test_external_update_time_unset() {
+		$woo_product = WC_Helper_Product::create_simple_product();
+		$woo_product->set_date_modified(null);
+
+		$fb_product = new \WC_Facebook_Product( $woo_product );
+		$data = $fb_product->prepare_product();
+
+		$this->assertEquals(isset($data['external_update_time']), false);
+	}
 }