diff --git a/ipfix/message.py b/ipfix/message.py
index 0af2fad..71c1328 100644
--- a/ipfix/message.py
+++ b/ipfix/message.py
@@ -398,7 +398,7 @@ def record_iterator(self,
             offset += _sethdr_st.size # skip set header in decode
             if setid == template.TEMPLATE_SET_ID or\
                setid == template.OPTIONS_SET_ID:
-                while offset < setend:
+                while offset + 4 < setend: # allow for padding up to 4 byte alignment
                     (tmpl, offset) = template.decode_template_from(
                                               self.mbuf, offset, setid)
                     # FIXME handle withdrawal
@@ -431,6 +431,7 @@ def record_iterator(self,
                         # KeyError on template lookup - unknown data set
                         self.unknown_data_set_hook(self,
                                      self.mbuf[offset-_sethdr_st.size:setend])
+            offset = setend     # real end may be greater that accumulated offset
 
     def namedict_iterator(self):
         """
diff --git a/ipfix/template.py b/ipfix/template.py
index 1203e55..26cd8c1 100644
--- a/ipfix/template.py
+++ b/ipfix/template.py
@@ -187,7 +187,7 @@ def decode_from(self, buf, offset, packplan = None):
         offset += packplan.st.size
 
         # short circuit on no varlen
-        if not self.varlenslice:
+        if self.varlenslice is None:
             return (vals, offset)
 
         # direct iteration over remaining IEs
@@ -239,7 +239,7 @@ def encode_to(self, buf, offset, vals, packplan = None):
         offset += packplan.st.size
 
         # shortcircuit no varlen
-        if not self.varlenslice:
+        if self.varlenslice is None:
             return offset
 
         # direct iteration over remaining IEs