diff --git a/gem/impero_utils.py b/gem/impero_utils.py
index e5635975..6dea6f5f 100644
--- a/gem/impero_utils.py
+++ b/gem/impero_utils.py
@@ -10,6 +10,8 @@
 from functools import singledispatch
 from itertools import chain, groupby
 
+from numpy import find_common_type
+
 from gem.node import traversal, collect_refcount
 from gem import gem, impero as imp, optimise, scheduling
 
@@ -21,7 +23,9 @@
 #     temporaries - List of GEM expressions which have assigned temporaries
 #     declare     - Where to declare temporaries to get correct C code
 #     indices     - Indices for declarations and referencing values
-ImperoC = collections.namedtuple('ImperoC', ['tree', 'temporaries', 'declare', 'indices'])
+#     return_variable - 2-tuple of gem return variable and inferred numpy dtype
+ImperoC = collections.namedtuple('ImperoC', ['tree', 'temporaries', 'declare', 'indices',
+                                             'return_variable'])
 
 
 class NoopError(Exception):
@@ -38,11 +42,12 @@ def preprocess_gem(expressions, replace_delta=True, remove_componenttensors=True
     return expressions
 
 
-def compile_gem(assignments, prefix_ordering, remove_zeros=False):
+def compile_gem(assignments, prefix_ordering, scalar_type, remove_zeros=False):
     """Compiles GEM to Impero.
 
     :arg assignments: list of (return variable, expression DAG root) pairs
     :arg prefix_ordering: outermost loop indices
+    :arg scalar_type: default scalar type
     :arg remove_zeros: remove zero assignment to return variables
     """
     # Remove zeros
@@ -52,6 +57,9 @@ def nonzero(assignment):
             return not isinstance(expression, gem.Zero)
         assignments = list(filter(nonzero, assignments))
 
+    # Type inference for return value
+    return_variable = infer_dtype(assignments, scalar_type)
+
     # Just the expressions
     expressions = [expression for variable, expression in assignments]
 
@@ -88,7 +96,26 @@ def nonzero(assignment):
     declare, indices = place_declarations(tree, temporaries, get_indices)
 
     # Prepare ImperoC (Impero AST + other data for code generation)
-    return ImperoC(tree, temporaries, declare, indices)
+    return ImperoC(tree, temporaries, declare, indices, return_variable)
+
+
+def infer_dtype(assignments, scalar_type):
+    from tsfc.loopy import assign_dtypes
+    from gem.node import traversal
+
+    def extract_variable(expr):
+        x, = set(v for v in traversal([expr]) if isinstance(v, gem.Variable))
+        return x
+
+    vars = set()
+    dtypes = set()
+    for var, expression in assignments:
+        var = extract_variable(var)
+        ((_, dtype), ) = assign_dtypes([expression], scalar_type)
+        vars.add(var)
+        dtypes.add(dtype)
+    var, = vars
+    return var, find_common_type([], dtypes)
 
 
 def make_prefix_ordering(indices, prefix_ordering):
diff --git a/tests/test_codegen.py b/tests/test_codegen.py
index 8d0bc796..3cc660de 100644
--- a/tests/test_codegen.py
+++ b/tests/test_codegen.py
@@ -1,4 +1,5 @@
 import pytest
+import numpy
 
 from gem import impero_utils
 from gem.gem import Index, Indexed, IndexSum, Product, Variable
@@ -18,7 +19,7 @@ def make_expression(i, j):
     e2 = make_expression(i, i)
 
     def gencode(expr):
-        impero_c = impero_utils.compile_gem([(Ri, expr)], (i, j))
+        impero_c = impero_utils.compile_gem([(Ri, expr)], (i, j), numpy.dtype(numpy.float64))
         return impero_c.tree
 
     assert len(gencode(e1).children) == len(gencode(e2).children)
diff --git a/tsfc/driver.py b/tsfc/driver.py
index cc98895d..131b45ac 100644
--- a/tsfc/driver.py
+++ b/tsfc/driver.py
@@ -239,7 +239,8 @@ def compile_integral(integral_data, form_data, prefix, parameters, interface, co
                                            for var in return_variables]))
     index_ordering = tuple(quadrature_indices) + split_argument_indices
     try:
-        impero_c = impero_utils.compile_gem(assignments, index_ordering, remove_zeros=True)
+        impero_c = impero_utils.compile_gem(assignments, index_ordering,
+                                            parameters["scalar_type"], remove_zeros=True)
     except impero_utils.NoopError:
         # No operations, construct empty kernel
         return builder.construct_empty_kernel(kernel_name)
@@ -421,7 +422,8 @@ def compile_expression_dual_evaluation(expression, to_element, coordinates, inte
     # TODO: one should apply some GEM optimisations as in assembly,
     # but we don't for now.
     ir, = impero_utils.preprocess_gem([ir])
-    impero_c = impero_utils.compile_gem([(return_expr, ir)], return_indices)
+    impero_c = impero_utils.compile_gem([(return_expr, ir)], return_indices,
+                                        parameters["scalar_type"])
     index_names = dict((idx, "p%d" % i) for (i, idx) in enumerate(basis_indices))
     # Handle kernel interface requirements
     builder.register_requirements([ir])
diff --git a/tsfc/fem.py b/tsfc/fem.py
index 1726c468..b8d580b3 100644
--- a/tsfc/fem.py
+++ b/tsfc/fem.py
@@ -67,6 +67,14 @@ def __init__(self, interface, **kwargs):
             raise ValueError("unexpected keyword argument '{0}'".format(invalid_keywords.pop()))
         self.__dict__.update(kwargs)
 
+    def reify(self, expr):
+        if self.complex_mode:
+            indices = gem.indices(len(expr.shape))
+            return gem.ComponentTensor(gem.MathFunction("real", gem.Indexed(expr, indices)),
+                                       indices)
+        else:
+            return expr
+
     @cached_property
     def fiat_cell(self):
         return as_fiat_cell(self.ufl_cell)
@@ -136,7 +144,7 @@ def config(self):
         return config
 
     def cell_size(self):
-        return self.interface.cell_size(self.mt.restriction)
+        return self.interface.reify(self.interface.cell_size(self.mt.restriction))
 
     def jacobian_at(self, point):
         expr = Jacobian(self.mt.terminal.ufl_domain())
@@ -427,7 +435,7 @@ def translate_spatialcoordinate(terminal, mt, ctx):
     # Rebuild modified terminal
     expr = construct_modified_terminal(mt, terminal)
     # Translate replaced UFL snippet
-    return ctx.translator(expr)
+    return ctx.reify(ctx.translator(expr))
 
 
 class CellVolumeKernelInterface(ProxyKernelInterface):
diff --git a/tsfc/kernel_interface/firedrake.py b/tsfc/kernel_interface/firedrake.py
index a7321edf..816e69dd 100644
--- a/tsfc/kernel_interface/firedrake.py
+++ b/tsfc/kernel_interface/firedrake.py
@@ -27,7 +27,7 @@ def make_builder(*args, **kwargs):
 class Kernel(object):
     __slots__ = ("ast", "integral_type", "oriented", "subdomain_id",
                  "domain_number", "needs_cell_sizes", "tabulations", "quadrature_rule",
-                 "coefficient_numbers", "__weakref__")
+                 "return_dtype", "coefficient_numbers", "__weakref__")
     """A compiled Kernel object.
 
     :kwarg ast: The COFFEE ast for the kernel.
@@ -40,12 +40,14 @@ class Kernel(object):
     :kwarg coefficient_numbers: A list of which coefficients from the
         form the kernel needs.
     :kwarg quadrature_rule: The finat quadrature rule used to generate this kernel
+    :kwarg return_dtype: numpy dtype of the return value.
     :kwarg tabulations: The runtime tabulations this kernel requires
     :kwarg needs_cell_sizes: Does the kernel require cell sizes.
     """
     def __init__(self, ast=None, integral_type=None, oriented=False,
                  subdomain_id=None, domain_number=None, quadrature_rule=None,
                  coefficient_numbers=(),
+                 return_dtype=None,
                  needs_cell_sizes=False):
         # Defaults
         self.ast = ast
@@ -55,6 +57,7 @@ def __init__(self, ast=None, integral_type=None, oriented=False,
         self.subdomain_id = subdomain_id
         self.coefficient_numbers = coefficient_numbers
         self.needs_cell_sizes = needs_cell_sizes
+        self.return_dtype = return_dtype
         super(Kernel, self).__init__()
 
 
diff --git a/tsfc/kernel_interface/firedrake_loopy.py b/tsfc/kernel_interface/firedrake_loopy.py
index 4eb86afe..915b8360 100644
--- a/tsfc/kernel_interface/firedrake_loopy.py
+++ b/tsfc/kernel_interface/firedrake_loopy.py
@@ -27,7 +27,7 @@ def make_builder(*args, **kwargs):
 class Kernel(object):
     __slots__ = ("ast", "integral_type", "oriented", "subdomain_id",
                  "domain_number", "needs_cell_sizes", "tabulations", "quadrature_rule",
-                 "coefficient_numbers", "__weakref__")
+                 "return_dtype", "coefficient_numbers", "__weakref__")
     """A compiled Kernel object.
 
     :kwarg ast: The loopy kernel object.
@@ -40,12 +40,14 @@ class Kernel(object):
     :kwarg coefficient_numbers: A list of which coefficients from the
         form the kernel needs.
     :kwarg quadrature_rule: The finat quadrature rule used to generate this kernel
+    :kwarg return_dtype: numpy dtype of the return value.
     :kwarg tabulations: The runtime tabulations this kernel requires
     :kwarg needs_cell_sizes: Does the kernel require cell sizes.
     """
     def __init__(self, ast=None, integral_type=None, oriented=False,
                  subdomain_id=None, domain_number=None, quadrature_rule=None,
                  coefficient_numbers=(),
+                 return_dtype=None,
                  needs_cell_sizes=False):
         # Defaults
         self.ast = ast
@@ -55,6 +57,7 @@ def __init__(self, ast=None, integral_type=None, oriented=False,
         self.subdomain_id = subdomain_id
         self.coefficient_numbers = coefficient_numbers
         self.needs_cell_sizes = needs_cell_sizes
+        self.return_dtype = return_dtype
         super(Kernel, self).__init__()
 
 
@@ -164,8 +167,8 @@ def construct_kernel(self, return_arg, impero_c, precision, index_names):
         for name_, shape in self.tabulations:
             args.append(lp.GlobalArg(name_, dtype=self.scalar_type, shape=shape))
 
-        loopy_kernel = generate_loopy(impero_c, args, precision, self.scalar_type,
-                                      "expression_kernel", index_names)
+        loopy_kernel, _ = generate_loopy(impero_c, args, precision, self.scalar_type,
+                                         "expression_kernel", index_names, ignore_return_type=True)
         return ExpressionKernel(loopy_kernel, self.oriented, self.cell_sizes,
                                 self.coefficients, self.tabulations)
 
@@ -207,6 +210,7 @@ def set_arguments(self, arguments, multiindices):
         :arg multiindices: GEM argument multiindices
         :returns: GEM expression representing the return variable
         """
+        self.rank = len(arguments)
         self.local_tensor, expressions = prepare_arguments(
             arguments, multiindices, self.scalar_type, interior_facet=self.interior_facet,
             diagonal=self.diagonal)
@@ -277,7 +281,11 @@ def construct_kernel(self, name, impero_c, precision, index_names, quadrature_ru
         :returns: :class:`Kernel` object
         """
 
-        args = [self.local_tensor, self.coordinates_arg]
+        ignore_return_type = self.rank > 0
+        if ignore_return_type:
+            args = [self.local_tensor, self.coordinates_arg]
+        else:
+            args = [self.coordinates_arg]
         if self.kernel.oriented:
             args.append(self.cell_orientations_loopy_arg)
         if self.kernel.needs_cell_sizes:
@@ -292,8 +300,11 @@ def construct_kernel(self, name, impero_c, precision, index_names, quadrature_ru
             args.append(lp.GlobalArg(name_, dtype=self.scalar_type, shape=shape))
 
         self.kernel.quadrature_rule = quadrature_rule
-        self.kernel.ast = generate_loopy(impero_c, args, precision,
-                                         self.scalar_type, name, index_names)
+        ast, dtype = generate_loopy(impero_c, args, precision,
+                                    self.scalar_type, name, index_names,
+                                    ignore_return_type=ignore_return_type)
+        self.kernel.ast = ast
+        self.kernel.return_dtype = dtype
         return self.kernel
 
     def construct_empty_kernel(self, name):
diff --git a/tsfc/loopy.py b/tsfc/loopy.py
index e04ba2ba..b761ec0f 100644
--- a/tsfc/loopy.py
+++ b/tsfc/loopy.py
@@ -186,15 +186,17 @@ def active_indices(mapping, ctx):
         ctx.active_indices.pop(key)
 
 
-def generate(impero_c, args, precision, scalar_type, kernel_name="loopy_kernel", index_names=[]):
+def generate(impero_c, args, precision, scalar_type, kernel_name="loopy_kernel", index_names=[],
+             ignore_return_type=True):
     """Generates loopy code.
 
     :arg impero_c: ImperoC tuple with Impero AST and other data
     :arg args: list of loopy.GlobalArgs
     :arg precision: floating-point precision for printing
-    :arg scalar_type: type of scalars as C typename string
+    :arg scalar_type: type of scalars as numpy dtype
     :arg kernel_name: function name of the kernel
     :arg index_names: pre-assigned index names
+    :arg ignore_return_type: Ignore inferred return type from impero_c?
     :returns: loopy kernel
     """
     ctx = LoopyContext()
@@ -205,7 +207,12 @@ def generate(impero_c, args, precision, scalar_type, kernel_name="loopy_kernel",
     ctx.epsilon = 10.0 ** (-precision)
 
     # Create arguments
-    data = list(args)
+    if ignore_return_type:
+        return_dtype = scalar_type
+        data = list(args)
+    else:
+        A, return_dtype = impero_c.return_variable
+        data = [lp.GlobalArg(A.name, shape=A.shape, dtype=return_dtype)] + list(args)
     for i, (temp, dtype) in enumerate(assign_dtypes(impero_c.temporaries, scalar_type)):
         name = "t%d" % i
         if isinstance(temp, gem.Constant):
@@ -240,7 +247,7 @@ def generate(impero_c, args, precision, scalar_type, kernel_name="loopy_kernel",
         insn_new.append(insn.copy(priority=len(knl.instructions) - i))
     knl = knl.copy(instructions=insn_new)
 
-    return knl
+    return knl, return_dtype
 
 
 @singledispatch