diff --git a/smop/Makefile b/smop/Makefile
index bdcc5998..eacc1ec6 100644
--- a/smop/Makefile
+++ b/smop/Makefile
@@ -27,14 +27,14 @@ go_m: solver.m
 	octave -q go.m
 
 clean:
-	rm -f a.* *.pyc solver.so solver.py runtime.so
+	rm -f a.* *.pyc solver.so solver.py octave.so
 
 solver.py: solver.m r8_random.m 
 	$(PYTHON) main.py $^ -o $@
 
 check:
-	$(PYTHON) runtime.py 
-	$(PYTHON) test_runtime.py
+	$(PYTHON) octave.py 
+	$(PYTHON) test_core.py
 	$(PYTHON) test_matlabarray.py
 	$(PYTHON) test_sparsearray.py
 	$(PYTHON) test_lexer.py 
diff --git a/smop/backend.py b/smop/backend.py
index 0ea72092..d0de0ac6 100644
--- a/smop/backend.py
+++ b/smop/backend.py
@@ -45,7 +45,7 @@ def _backend(self,level=0):
         return " + ".join(a._backend() for a in self.args)
     else:
         #import pdb; pdb.set_trace()
-        return "[%s]" % self.args[0]._backend()
+        return "np.r_[%s]" % self.args[0]._backend()
 
 @extend(node.cellarrayref)
 def _backend(self,level=0):
diff --git a/smop/test_runtime.py b/smop/test_core.py
similarity index 99%
rename from smop/test_runtime.py
rename to smop/test_core.py
index 9050bdd4..c3c2c9d9 100644
--- a/smop/test_runtime.py
+++ b/smop/test_core.py
@@ -4,7 +4,7 @@
 # MIT license
 import numpy as np
 import unittest
-from runtime import *
+from core import *
 
 class Getitem(unittest.TestCase):
     def setUp(self):
diff --git a/smop/test_matlabarray.py b/smop/test_matlabarray.py
index 8ae1d0ea..5c702b7a 100644
--- a/smop/test_matlabarray.py
+++ b/smop/test_matlabarray.py
@@ -1,5 +1,5 @@
 import unittest
-from runtime import *
+from core import *
 
 class test_matlabarray(unittest.TestCase):
     """Expanding matlabarray"""
diff --git a/smop/test_sparsearray.py b/smop/test_sparsearray.py
index 863a128b..bb5f5d8c 100644
--- a/smop/test_sparsearray.py
+++ b/smop/test_sparsearray.py
@@ -1,6 +1,6 @@
 import numpy as np
 import unittest
-from runtime import *
+from core import *
 from sparsearray import sparsearray
 
 class Slice(unittest.TestCase):