--- a/PDSim/recip/_recip.pxd
+++ b/PDSim/recip/_recip.pxd
@@ -1,5 +1,5 @@
-from PDSim.misc._listmath import listm
-from PDSim.misc._listmath cimport listm
+from PDSim.misc.datatypes import arraym
+from PDSim.misc.datatypes cimport arraym
 
 cdef class _Recip(object):
     
@@ -8,5 +8,5 @@
     
     #Function prototypes
     cpdef tuple V_dV(self, double theta)
-    cpdef listm heat_transfer_callback(self, double theta)
+    cpdef arraym heat_transfer_callback(self, double theta)
     cpdef dict __cdict__(self)