diff --git a/SimPEG/Solver.py b/SimPEG/Solver.py
index 127a8c9f..d9ac4a1d 100644
--- a/SimPEG/Solver.py
+++ b/SimPEG/Solver.py
@@ -128,7 +128,7 @@ class Solver(object):
             x[i] = (b[i] - np.dot(ith_row[1:], x_vals[1:])) / ith_row[0]
         return x
 
-    def solveForward(self, backend='python'):
+    def solveForward(self, b, backend='python'):
         """
             Use solve instead of this interface.
 
@@ -152,7 +152,7 @@ class Solver(object):
             x[i] = (b[i] - np.dot(ith_row[:-1], x_vals[:-1])) / ith_row[-1]
         return x
 
-    def solveDiagonal(self, backend='python'):
+    def solveDiagonal(self, b, backend='python'):
         """
             Use solve instead of this interface.
 
diff --git a/SimPEG/forward/Problem.py b/SimPEG/forward/Problem.py
index 679e8686..395156a2 100644
--- a/SimPEG/forward/Problem.py
+++ b/SimPEG/forward/Problem.py
@@ -1,5 +1,6 @@
 import numpy as np
 from SimPEG.utils import mkvc, sdiag
+import scipy.sparse as sp
 norm = np.linalg.norm
 
 
diff --git a/SimPEG/forward/__init__.py b/SimPEG/forward/__init__.py
index a7c58967..33c9a6b1 100644
--- a/SimPEG/forward/__init__.py
+++ b/SimPEG/forward/__init__.py
@@ -1,4 +1,4 @@
 from Problem import *
-from DCProblem import DCProblem
+import DCProblem
 from LinearProblem import LinearProblem
 import ModelTransforms