1 files changed, 5 insertions, 1 deletions
diff --git a/synapse/python_dependencies.py b/synapse/python_dependencies.py
index cf1414b4db..1adbdd9421 100644
--- a/synapse/python_dependencies.py
+++ b/synapse/python_dependencies.py
@@ -41,7 +41,11 @@ REQUIREMENTS = {
 CONDITIONAL_REQUIREMENTS = {
     "web_client": {
         "matrix_angular_sdk>=0.6.8": ["syweb>=0.6.8"],
-    }
+    },
+    "preview_url": {
+        "lxml>=3.6.0": ["lxml"],
+        "netaddr>=0.7.18": ["netaddr"],
+    },
 }