*magit: firedrake.txt

diff --git a/firedrake/fc/driver.py b/firedrake/fc/driver.py
index 1fb0e92..93da812 100644
--- a/firedrake/fc/driver.py
+++ b/firedrake/fc/driver.py
@@ -2,6 +2,7 @@ from __future__ import absolute_import
 
 import numpy
 import time
+import collections
 
 from ufl.algorithms import compute_form_data
 
@@ -83,7 +84,7 @@ def compile_integral(integral, fd, prefix):
         decl = coffee.Decl("const int *restrict *restrict", coffee.Symbol("cell_orientations"))
         arglist.insert(2, decl)
 
-    index_extents = {}
+    index_extents = collections.OrderedDict()
     for e in simplified:
         index_extents.update(ein.collect_index_extents(e))
     index_ordering = apply_prefix_ordering(index_extents.keys(),
diff --git a/firedrake/fc/einstein.py b/firedrake/fc/einstein.py
index 2eb824d..2af258c 100644
--- a/firedrake/fc/einstein.py
+++ b/firedrake/fc/einstein.py
@@ -514,7 +514,7 @@ def inline_indices(expression):
 
 
 def collect_index_extents(expression):
-    result = {}
+    result = collections.OrderedDict()
 
     for node in traversal([expression]):
         if isinstance(node, Indexed):
diff --git a/firedrake/fc/scheduling.py b/firedrake/fc/scheduling.py
index 3cccbc5..db97627 100644
--- a/firedrake/fc/scheduling.py
+++ b/firedrake/fc/scheduling.py
@@ -8,10 +8,20 @@ from firedrake.fc import einstein as ein, impero as imp
 from firedrake.fc.node import traversal
 
 
+class OrderedDefaultDict(collections.OrderedDict):
+    def __init__(self, factory, *args, **kwargs):
+        self.factory = factory
+        super(OrderedDefaultDict, self).__init__(*args, **kwargs)
+
+    def __missing__(self, key):
+        val = self[key] = self.factory()
+        return val
+
+
 class Queue(object):
     def __init__(self, reference_count, get_indices):
         self.waiting = reference_count.copy()
-        self.queue = collections.defaultdict(list)
+        self.queue = OrderedDefaultDict(list)
         self.get_indices = get_indices
 
     def reference(self, o):