diff --git a/product/ERP5Type/patches/ppml.py b/product/ERP5Type/patches/ppml.py
index 92a1b79debb7d38240ce95f24553511b7614667b..6c181c64c91bc7daa213b1e3d9299b4b6e0e41b9 100644
--- a/product/ERP5Type/patches/ppml.py
+++ b/product/ERP5Type/patches/ppml.py
@@ -45,9 +45,7 @@ def convert(S, find=None):
     ###              [\x00-\x1f] characters will be escaped to make a more
     ###              readable output.
     try:
-        if isinstance(S, unicode):
-            S = S.encode('utf8')
-        else:
+        if not isinstance(S, unicode):
             S.decode('utf8')
     except UnicodeDecodeError:
         new = ''.join([reprs3.get(x) for x in S])