diff --git a/ifupdown/iface.py b/ifupdown/iface.py
index 79840f9..7e3f849 100644
--- a/ifupdown/iface.py
+++ b/ifupdown/iface.py
@@ -392,6 +392,8 @@ class iface():
         if self.addr_method != dstiface.addr_method: return False
         if self.auto != dstiface.auto: return False
         if self.classes != dstiface.classes: return False
+        if len(self.config) != len(dstiface.config):
+            return False
         if any(True for k in self.config if k not in dstiface.config):
             return False
         if any(True for k,v in self.config.items()