diff --git a/server/hra/web/html.py b/server/hra/web/html.py
index 88901ce..d422e1d 100644
--- a/server/hra/web/html.py
+++ b/server/hra/web/html.py
@@ -11,7 +11,7 @@ class EscapeError(RuntimeError):
 
 
 def escape_attribute(x:str) -> str:
-    return x.replace("&", "&").replace('"', """)
+    return str(x).replace("&", "&").replace('"', """)
 
 
 def escape_attribute_name(x:str) -> str: