diff --git a/pylops/signalprocessing/fredholm1.py b/pylops/signalprocessing/fredholm1.py
index 8a64e12b..57eec234 100644
--- a/pylops/signalprocessing/fredholm1.py
+++ b/pylops/signalprocessing/fredholm1.py
@@ -61,7 +61,7 @@ class Fredholm1(LinearOperator):
         d(k, x, z) = \int{G(k, x, y) m(k, y, z) \,\mathrm{d}y}
         \quad \forall k=1,\ldots,n_{slice}
 
-    on the other hand its adjoin is expressed as
+    on the other hand its adjoint is expressed as
 
     .. math::
 
@@ -146,4 +146,4 @@ def _rmatvec(self, x: NDArray) -> NDArray:
                 for isl in range(self.nsl):
                     # y[isl] = ncp.dot(self.G[isl].conj().T, x[isl])
                     y[isl] = ncp.dot(x[isl].T.conj(), self.G[isl]).T.conj()
-        return y.ravel()
+        return y
diff --git a/pylops/waveeqprocessing/mdd.py b/pylops/waveeqprocessing/mdd.py
index 0202b624..90e2cba3 100644
--- a/pylops/waveeqprocessing/mdd.py
+++ b/pylops/waveeqprocessing/mdd.py
@@ -242,6 +242,7 @@ def MDC(
         conj=conj,
         prescaled=prescaled,
         args_FFT={"engine": fftengine},
+        args_FFT1={"engine": fftengine},
         args_Fredholm1={"usematmul": usematmul},
     )
     MOp.name = name