diff --git a/plugins/libkolab/composer.json b/plugins/libkolab/composer.json
index dc15b632..f9a714f8 100644
--- a/plugins/libkolab/composer.json
+++ b/plugins/libkolab/composer.json
@@ -26,6 +26,7 @@
     "require": {
         "php": ">=5.3.0",
         "roundcube/plugin-installer": ">=0.1.3",
-        "caxy/php-htmldiff": "dev-master"
+        "pear/http_request2": "~2.3.0",
+        "caxy/php-htmldiff": "~0.1.7"
     }
 }