diff --git a/lib/diaspora_federation/discovery/exceptions.rb b/lib/diaspora_federation/discovery/exceptions.rb
index 38c536a..caba207 100644
--- a/lib/diaspora_federation/discovery/exceptions.rb
+++ b/lib/diaspora_federation/discovery/exceptions.rb
@@ -1,7 +1,11 @@
 module DiasporaFederation
   module Discovery
+    # Raised, if there is an error while discover a new person
+    class DiscoveryError < RuntimeError
+    end
+
     # Raised, if the XML structure is invalid
-    class InvalidDocument < RuntimeError
+    class InvalidDocument < DiscoveryError
     end
 
     # Raised, if something is wrong with the webfinger data
@@ -9,11 +13,7 @@ module DiasporaFederation
     # * if the +webfinger_url+ is missing or malformed in {HostMeta.from_base_url} or {HostMeta.from_xml}
     # * if the parsed XML from {WebFinger.from_xml} is incomplete
     # * if the html passed to {HCard.from_html} in some way is malformed, invalid or incomplete.
-    class InvalidData < RuntimeError
-    end
-
-    # Raised, if there is an error while discover a new person
-    class DiscoveryError < RuntimeError
+    class InvalidData < DiscoveryError
     end
   end
 end