diff --git a/plugins/Math/local/convertcore.py b/plugins/Math/local/convertcore.py
index c89955891..75d38fa11 100644
--- a/plugins/Math/local/convertcore.py
+++ b/plugins/Math/local/convertcore.py
@@ -1177,6 +1177,12 @@ class Unit:
     def __cmp__(self, other):
         return cmp(self.name, other.name)
 
+    def __lt__(self, other):
+        return self.name < other.name
+
+    def __eq__(self, other):
+        return self.name == other.name
+
 ############################################################################
 # Wrapper functionality
 #