diff --git a/brozzler/site.py b/brozzler/site.py
index f474d9b..1dcd90f 100644
--- a/brozzler/site.py
+++ b/brozzler/site.py
@@ -54,11 +54,15 @@ class Url:
         return self._host
 
     def matches_ip_or_domain(self, ip_or_domain):
-        """Returns true if
-           - ip_or_domain is an ip address and self.host is the same ip address
-           - ip_or_domain is a domain and self.host is the same domain
-           - ip_or_domain is a domain and self.host is a subdomain of it
         """
+        Returns true if
+         - ip_or_domain is an ip address and self.host is the same ip address
+         - ip_or_domain is a domain and self.host is the same domain
+         - ip_or_domain is a domain and self.host is a subdomain of it
+        """
+        if not self.host:
+            return False
+
         if ip_or_domain == self.host:
             return True
 
diff --git a/setup.py b/setup.py
index ac5d53a..e9888b6 100644
--- a/setup.py
+++ b/setup.py
@@ -32,7 +32,7 @@ def find_package_data(package):
 
 setuptools.setup(
         name='brozzler',
-        version='1.1b7.dev107',
+        version='1.1b7.dev108',
         description='Distributed web crawling with browsers',
         url='https://github.com/internetarchive/brozzler',
         author='Noah Levitt',