diff --git a/pyop2/global_kernel.py b/pyop2/global_kernel.py
index d49a2a5de..9b2f1df7b 100644
--- a/pyop2/global_kernel.py
+++ b/pyop2/global_kernel.py
@@ -294,7 +294,7 @@ def __init__(self, local_kernel, arguments, *,
                  subset=False,
                  iteration_region=None,
                  pass_layer_arg=False,
-                 form_signature=None):
+                 signature=None):
         if self._initialized:
             return
 
@@ -329,7 +329,7 @@ def __init__(self, local_kernel, arguments, *,
         self._subset = subset
         self._iteration_region = iteration_region
         self._pass_layer_arg = pass_layer_arg
-        self._form_signature = form_signature
+        self.signature = signature
 
         # Cache for stashing the compiled code
         self._func_cache = {}
diff --git a/pyop2/types/dataset.py b/pyop2/types/dataset.py
index 13ad7904f..6af860b4f 100644
--- a/pyop2/types/dataset.py
+++ b/pyop2/types/dataset.py
@@ -183,7 +183,7 @@ def local_ises(self):
     def layout_vec(self):
         """A PETSc Vec compatible with the dof layout of this DataSet."""
         vec = PETSc.Vec().create(comm=self.comm)
-        size = (self.size * self.cdim - self.set.constrained_size, None)
+        size = ((self.size - self.set.constrained_size) * self.cdim, None)
         vec.setSizes(size, bsize=self.cdim)
         vec.setUp()
         return vec
diff --git a/pyop2/types/set.py b/pyop2/types/set.py
index 607d5098a..2bfbf962e 100644
--- a/pyop2/types/set.py
+++ b/pyop2/types/set.py
@@ -64,7 +64,7 @@ def _wrapper_cache_key_(self):
 
     @utils.validate_type(('size', (numbers.Integral, tuple, list, np.ndarray), ex.SizeTypeError),
                          ('name', str, ex.NameTypeError))
-    def __init__(self, size, name=None, halo=None, comm=None, constrained_nodes=0):
+    def __init__(self, size, name=None, halo=None, comm=None, constrained_size=0):
         self.comm = mpi.internal_comm(comm, self)
         if isinstance(size, numbers.Integral):
             size = [size] * 3
@@ -75,7 +75,7 @@ def __init__(self, size, name=None, halo=None, comm=None, constrained_nodes=0):
         self._name = name or "set_#x%x" % id(self)
         self._halo = halo
         self._partition_size = 1024
-        self._constrained_size = constrained_nodes
+        self._constrained_size = constrained_size
 
         # A cache of objects built on top of this set
         self._cache = {}