diff --git a/LCS/pyparameterset/src/__init__.py b/LCS/pyparameterset/src/__init__.py
index 7c711b50002c3a0453931c6d7ef42cac0d851b4d..e9f1f9e551e24768ad3aef4f4d268f51a49a6eac 100755
--- a/LCS/pyparameterset/src/__init__.py
+++ b/LCS/pyparameterset/src/__init__.py
@@ -80,9 +80,25 @@ class parameterset(PyParameterSet):
         """Get the parametervalue object of a parameter."""
         return self._get (key)
 
-    def makeSubset (self, prefix):
-        """Get a subset of all keys starting with the given prefix"""
-        ps = self._makeSubset (prefix)
+    def makeSubset (self, baseKey, prefix=''):
+        """Return a subset as a new parameterset object.
+        
+        baseKey
+          The leading part of the parameter name denoting the subset.
+          A trailing period needs to be given.
+        prefix
+          The baseKey parameter name part is replaced by this new prefix.
+          The default new prefix is empty.
+
+        For example::
+
+          newps = ps.makeSubset ('p1.p2.', 'pr.')
+          
+        creates a subset of all keys starting with `p1.p2.` and replaces
+        that prefix by `pr.`.
+
+        """
+        ps = self._makeSubset (baseKey, prefix)
         return parameterset (ps, _copyObj=True)
 
     def keys(self):
diff --git a/LCS/pyparameterset/src/pyparameterset.cc b/LCS/pyparameterset/src/pyparameterset.cc
index bd583c9a3731e2030bb4a132c41547f0bf241964..c3473b240cd55bd6ccd9450013f7724119e3f9d8 100644
--- a/LCS/pyparameterset/src/pyparameterset.cc
+++ b/LCS/pyparameterset/src/pyparameterset.cc
@@ -172,27 +172,10 @@ namespace LOFAR {
             "Get the software version.")
       .def ("size", &ParameterSet::size,
             "Get the number of parameters.")
-      .def ("__len__", &ParameterSet::size,
-            "Get the number of parameters.")
       .def ("keywords", &PyParameterSet::keywords)
       .def ("_makeSubset", &PyParameterSet::makeSubset,
  	    (boost::python::arg("baseKey"),
-             boost::python::arg("prefix")=""),
-            "Return a subset as a new parameterset object.\n"
-            "\n"
-            "baseKey\n"
-            "  The leading part of the parameter name denoting the subset.\n"
-            "  A trailing period has to be given.\n"
-            "prefix\n"
-            "  The baseKey parameter name part is replaced by the prefix.\n"
-            "\n"
-            "For example::\n"
-            "\n"
-            "  newps = ps.makeSubset ('p1,p2,', 'pr.')\n"
-            "\n"
-            "creates a subset of all keys starting with `p`1.p2.` and replaces\n"
-            "that prefix by `pr.`.\n"
-            )
+             boost::python::arg("prefix")))
       .def ("subtractSubset", &ParameterSet::subtractSubset,
  	    (boost::python::arg("baseKey")),
             "Remove all parameters starting with the baseKey.")
diff --git a/LCS/pyparameterset/test/tpyparameterset.py b/LCS/pyparameterset/test/tpyparameterset.py
index 85ad29925b9797ce25bda439071e1c56cadf2597..be0dd2cd79b183950a98d4add4bb4b9c1bea2f22 100644
--- a/LCS/pyparameterset/test/tpyparameterset.py
+++ b/LCS/pyparameterset/test/tpyparameterset.py
@@ -84,7 +84,7 @@ checkps (ps)
 pss = ps.makeSubset('a.')
 print pss.keys()
 print 'b.c =', pss.getString ('b.c')
-print pss.makeSubset('b.').keys()
+print pss.makeSubset('b.', 'aa.bb.').keys()
 print pss.makeSubset('b.').size()
 print pss.makeSubset('cc').keys()    # should be empty
 print len(pss.makeSubset('cc'))
diff --git a/LCS/pyparameterset/test/tpyparameterset.stdout b/LCS/pyparameterset/test/tpyparameterset.stdout
index 9f0374a92607ca4f10b93901dba4a2c71b85a4b5..d11dc795152badf639efae6bf85e38e2a36b202b 100644
--- a/LCS/pyparameterset/test/tpyparameterset.stdout
+++ b/LCS/pyparameterset/test/tpyparameterset.stdout
@@ -80,7 +80,7 @@ True
 [5, 6, 7, 8, 9, 10]
 ['b', 'b.bool', 'b.c', 'b.double', 'b.lange_naam']
 b.c = 5
-['bool', 'c', 'double', 'lange_naam']
+['aa.bb.bool', 'aa.bb.c', 'aa.bb.double', 'aa.bb.lange_naam']
 4
 []
 0