diff --git a/simpegEM/TDEM/TDEM_b.py b/simpegEM/TDEM/TDEM_b.py
index 7f00485b..2eada637 100644
--- a/simpegEM/TDEM/TDEM_b.py
+++ b/simpegEM/TDEM/TDEM_b.py
@@ -93,7 +93,7 @@ class ProblemTDEM_b(ProblemBaseTDEM):
         f = FieldsTDEM(self.mesh, 1, self.times.size, 'b')
         f.set_b(b, 0)
         f.set_e(e, 0)
-        for i in range(1,self.times.size):
+        for i in range(1,self.nTimes):
             dt = self.getDt(i)
             b = 1/dt*self.MfMui*u.get_b(i) + self.MfMui*self.mesh.edgeCurl*u.get_e(i) - 1/dt*self.MfMui*u.get_b(i-1)
             e = self.mesh.edgeCurl.T*self.MfMui*u.get_b(i) - self.MeSigma*u.get_e(i)
@@ -101,6 +101,25 @@ class ProblemTDEM_b(ProblemBaseTDEM):
             f.set_e(e, i)
         return f
 
+    def AhtVec(self, m, u=None):
+        if u is None:
+            u = self.fields(m)
+        self.makeMassMatrices(m)
+        f = FieldsTDEM(self.mesh, 1, self.times.size, 'b')
+        for i in range(self.nTimes-1):
+            b = 1/self.getDt(i)*self.MfMui*u.get_b(i) + self.MfMui*self.mesh.edgeCurl*u.get_e(i) - 1/self.getDt(i+1)*self.MfMui*u.get_b(i+1)
+            e = self.mesh.edgeCurl.T*self.MfMui*u.get_b(i) - self.MeSigma*u.get_e(i)
+            f.set_b(b, i)
+            f.set_e(e, i)
+        N = self.nTimes - 1
+        b = 1/self.getDt(N)*self.MfMui*u.get_b(N) + self.MfMui*self.mesh.edgeCurl*u.get_e(N)
+        e = self.mesh.edgeCurl.T*self.MfMui*u.get_b(N) - self.MeSigma*u.get_e(N)
+        f.set_b(b, N)
+        f.set_e(e, N)
+        return f
+
+
+
 if __name__ == '__main__':
     from SimPEG import *
     import simpegEM as EM
diff --git a/simpegEM/Tests/test_forward_EMproblem.py b/simpegEM/Tests/test_forward_EMproblem.py
index 1f5750d8..42ad57dd 100644
--- a/simpegEM/Tests/test_forward_EMproblem.py
+++ b/simpegEM/Tests/test_forward_EMproblem.py
@@ -69,7 +69,6 @@ class TDEM_bDerivTests(unittest.TestCase):
        self.prb.pair(self.dat)
        self.mesh = mesh
 
-
     def test_AhVec(self):
         """
             Test that fields and AhVec produce consistent results
@@ -233,7 +232,6 @@ class TDEM_bDerivTests(unittest.TestCase):
         passed = Tests.checkDerivative(derChk, sigma, plotIt=False, dx=d_sig, num=2, eps=1e-20)
         self.assertTrue(passed)
 
-
     def test_projectAdjoint(self):
         prb = self.prb
         dat = self.dat
@@ -252,6 +250,25 @@ class TDEM_bDerivTests(unittest.TestCase):
 
         self.assertTrue((V1-V2)/V1<1e-12)
 
+    def test_adjointAhVsAht(self):
+        prb = self.prb
+        mesh = self.mesh
+        sigma = self.sigma
+
+        f1 = EM.TDEM.FieldsTDEM(prb.mesh, 1, prb.nTimes, 'b')
+        for i in range(f1.nTimes):
+            f1.set_b(np.random.rand(mesh.nF, 1), i)
+            f1.set_e(np.random.rand(mesh.nE, 1), i)
+
+        f2 = EM.TDEM.FieldsTDEM(prb.mesh, 1, prb.nTimes, 'b')
+        for i in range(f2.nTimes):
+            f2.set_b(np.random.rand(mesh.nF, 1), i)
+            f2.set_e(np.random.rand(mesh.nE, 1), i)
+
+        V1 = f2.fieldVec().dot(prb.AhVec(sigma, f1).fieldVec())
+        V2 = f1.fieldVec().dot(prb.AhtVec(sigma, f2).fieldVec())
+        self.assertLess(np.abs(V1-V2)/V1, 1e-12)
+
 
 if __name__ == '__main__':
     unittest.main()