--- a/test/memorydb.py	Sat Jul 28 14:12:06 2018 +0100
+++ b/test/memorydb.py	Sat Jul 28 20:21:59 2018 +0100
@@ -259,6 +259,8 @@
         return '<memorydb instance at %x>'%id(self)
 
     def storefile(self, classname, nodeid, property, content):
+        if isinstance(content, str):
+            content = s2b(content)
         self.tx_files[classname, nodeid, property] = content
         self.transactions.append((self.doStoreFile, (classname, nodeid,
             property)))