diff --git a/ibis/backends/trino/__init__.py b/ibis/backends/trino/__init__.py
index cd0938efe853..20a6286fb5c0 100644
--- a/ibis/backends/trino/__init__.py
+++ b/ibis/backends/trino/__init__.py
@@ -298,7 +298,7 @@ def do_connect(
         """
         if (
             isinstance(auth, str)
-            and (scheme := urlparse(host).scheme)
+            and (scheme := urlparse(host).scheme) is not None
             and scheme != "http"
         ):
             auth = BasicAuthentication(user, auth)