diff --git a/install-dev/data/db_structure.sql b/install-dev/data/db_structure.sql
index f8c57eb97..3d17ef353 100644
--- a/install-dev/data/db_structure.sql
+++ b/install-dev/data/db_structure.sql
@@ -871,7 +871,8 @@ CREATE TABLE `PREFIX_image` (
   `cover` tinyint(1) unsigned NOT NULL default '0',
   PRIMARY KEY  (`id_image`),
   KEY `image_product` (`id_product`),
-  KEY `id_product_cover` (`id_product`,`cover`)
+  KEY `id_product_cover` (`id_product`,`cover`),
+  UNIQUE KEY `idx_product_image` (`id_image`, `id_product`, `cover`)
 ) ENGINE=ENGINE_TYPE DEFAULT CHARSET=utf8;
 
 CREATE TABLE `PREFIX_image_lang` (
diff --git a/install-dev/upgrade/php/add_missing_image_key.php b/install-dev/upgrade/php/add_missing_image_key.php
new file mode 100644
index 000000000..94c88138a
--- /dev/null
+++ b/install-dev/upgrade/php/add_missing_image_key.php
@@ -0,0 +1,18 @@
+<?php
+
+function add_missing_image_key()
+{
+	$res = true;
+	$key_exists = Db::getInstance()->executeS('SHOW INDEX
+		FROM `'._DB_PREFIX_.'image`
+		WHERE Key_name = \'idx_product_image\'');
+	if ($key_exists)
+		$res &= Db::getInstance()->execute('ALTER TABLE
+		`'._DB_PREFIX_.'image`
+		DROP KEY `idx_product_image`');
+	$res &= Db::getInstance()->execute('ALTER TABLE
+	`'._DB_PREFIX_.'image`
+	ADD UNIQUE `idx_product_image` (`id_image`, `id_product`, `cover`)');
+
+	return $res;
+}
diff --git a/install-dev/upgrade/sql/1.5.0.13.sql b/install-dev/upgrade/sql/1.5.0.13.sql
new file mode 100644
index 000000000..69c431ffd
--- /dev/null
+++ b/install-dev/upgrade/sql/1.5.0.13.sql
@@ -0,0 +1,3 @@
+SET NAMES 'utf8';
+
+/* PHP:add_missing_image_key(); */;