diff --git a/pylops_mpi/optimization/cls_basic.py b/pylops_mpi/optimization/cls_basic.py
index 9ad9a34e..457b3af8 100644
--- a/pylops_mpi/optimization/cls_basic.py
+++ b/pylops_mpi/optimization/cls_basic.py
@@ -373,7 +373,7 @@ def step(self, x: Union[DistributedArray, StackedDistributedArray],
 
         """
 
-        a = float(self.kold / (self.q.dot(self.q.conj()) + self.damp * self.c.dot(self.c.conj())))
+        a = float(np.abs(self.kold / (self.q.dot(self.q.conj()) + self.damp * self.c.dot(self.c.conj()))))
         x += a * self.c
         self.s -= a * self.q
         damped_x = self.damp * x
diff --git a/pylops_mpi/waveeqprocessing/MDC.py b/pylops_mpi/waveeqprocessing/MDC.py
index 391095f7..1d6524d8 100644
--- a/pylops_mpi/waveeqprocessing/MDC.py
+++ b/pylops_mpi/waveeqprocessing/MDC.py
@@ -173,5 +173,6 @@ def MPIMDC(G, nt, nv, nfreq, dt=1., dr=1., twosided=True,
                 saveGt=saveGt, conj=conj, prescaled=prescaled,
                 base_comm=base_comm,
                 _Fredholm1=MPIFredholm1,
-                args_FFT={'engine': fftengine},
+                args_FFT={"engine": fftengine},
+                args_FFT1={"engine": fftengine},
                 args_Fredholm1={'usematmul': usematmul})