diff --git a/python/dune/perftool/ufl/topsum.py b/python/dune/perftool/ufl/topsum.py
index 18b266cf644cf1c9709adc0faecf4698c97ac64e..5f79d6cc88ad4310813a5b78560686ea91497484 100644
--- a/python/dune/perftool/ufl/topsum.py
+++ b/python/dune/perftool/ufl/topsum.py
@@ -22,5 +22,4 @@ class TopSumSplit(MultiFunction):
             MultiFunction.__call__(self, op)
 
     def index_sum(self, o):
-        print "ISUM"
         MultiFunction.__call__(self, o.operands()[0])
diff --git a/python/dune/perftool/ufl/transformations/__init__.py b/python/dune/perftool/ufl/transformations/__init__.py
index 2ff2cd122d9d7f4ea4f8bfa13892682f22db249b..e723f548563feb4a0c41e128daf3d362d7f2c4b2 100644
--- a/python/dune/perftool/ufl/transformations/__init__.py
+++ b/python/dune/perftool/ufl/transformations/__init__.py
@@ -7,19 +7,26 @@ class TransformationWrapper(object):
         # Extract the name of the transformation from the given kwargs
         assert "name" in kwargs
         self.name = kwargs.pop("name")
+        self.printBefore = kwargs.pop("printBefore", True)
 
     def write_trafo(self, expr, before):
+        # Skip this if we explicitly disabled it
+        if before and not self.printBefore:
+            return
+
+        # Write out a dot file
         from dune.perftool.options import get_option
-        if get_option("print_transformations", False):
+        # TODO This should be siabled by default!
+        if get_option("print_transformations", True):
             import os
             dir = get_option("print_transformations_dir", os.getcwd())
             filename = "trafo_{}_{}_{}.dot".format(self.name, str(self.counter).zfill(4), "in" if before else "out")
-            filename = os.join(dir, filename)
+            filename = os.path.join(dir, filename)
             with open(filename,'w') as out:
-                from ufl.formatting import ufl2dot
-                out.write(ufl2dot(expr))
+                from ufl.formatting.ufl2dot import ufl2dot
+                out.write(str(ufl2dot(expr)[0]))
             if not before:
-                self._counter = self._counter + 1
+                self.counter = self.counter + 1
 
     def __call__(self, expr, *args, **kwargs):
         # We assume that the first argument to any transformation is the expression
@@ -47,3 +54,7 @@ def ufl_transformation(**kwargs):
     """ A decorator for ufl transformations. It allows us to output the
     result if needed. """
     return lambda f: TransformationWrapper(f, **kwargs)
+
+@ufl_transformation(name="print", printBefore=False)
+def print_expression(e):
+    return e
\ No newline at end of file
diff --git a/python/dune/perftool/ufl/validity.py b/python/dune/perftool/ufl/validity.py
index 9b91c2620b58bb33f97327556f95ab932506b06c..c8c77787de90513bc077d97877b2e212242f8a16 100644
--- a/python/dune/perftool/ufl/validity.py
+++ b/python/dune/perftool/ufl/validity.py
@@ -38,16 +38,22 @@ def check_validity(uflexpr):
     tss = TopSumSplit()
     ae = ArgumentExtractor()
 
+    def check(term, rank):
+        if not len(ae(term)) == rank:
+            from dune.perftool.ufl.transformations import print_expression
+            print_expression(term)
+            raise ValueError("Form not valid for pdelab code generation. Dumped dot file to send to dominic.kempf@iwr.uni-heidelberg.de")
+
     if isinstance(uflexpr, Form):
         rank = len(uflexpr.arguments())
         for integral in uflexpr.integrals():
             for term in tss(integral.integrand()):
-                assert len(ae(term)) == rank
+                check(term, rank)
         return
 
     if isinstance(uflexpr, Expr):
         rank = UFLRank()(uflexpr)
-        assert len(ae(uflexpr)) == rank
+        check(uflexpr, rank)
         return
 
     raise TypeError("Unknown object type in check_validity: {}".format(type(uflexpr)))