diff -r -U1 pyfeyn-1.0.0.orig/pyfeyn/feynml.py pyfeyn-1.0.0/pyfeyn/feynml.py
--- pyfeyn-1.0.0.orig/pyfeyn/feynml.py	2016-02-09 22:48:29.000000000 +0100
+++ pyfeyn-1.0.0/pyfeyn/feynml.py	2016-02-14 13:11:16.034537778 +0100
@@ -257,3 +257,3 @@
         if self.root.tag != "feynml":
-            raise "FeynML Error: <feynml> must be root element" % self.root.tag
+            raise Exception("FeynML Error: <feynml> must be root element" % self.root.tag)
         for element in self.root:
@@ -266,3 +266,3 @@
             else:
-                raise "FeynML Error: invalid top-level tag <%s>" % element.tag
+                raise Exception("FeynML Error: invalid top-level tag <%s>" % element.tag)
 
@@ -328,3 +328,3 @@
             except:
-                raise "FeynML Error: invalid bend amount %s for <propagator> element"%element.attrib["bend"]
+                raise Exception("FeynML Error: invalid bend amount %s for <propagator> element"%element.attrib["bend"])
         if "style" in element.attrib: