diff --git a/control/optimal.py b/control/optimal.py
index 3242ac3fb..6b60c5b25 100644
--- a/control/optimal.py
+++ b/control/optimal.py
@@ -746,9 +746,9 @@ def _compute_states_inputs(self, coeffs):
                 states = self.last_states
             else:
                 states = self._simulate_states(self.x, inputs)
-                self.last_x = self.x
-                self.last_states = states
-                self.last_coeffs = coeffs
+                self.last_x = self.x.copy()             # save initial state
+                self.last_states = states               # always a new object
+                self.last_coeffs = coeffs.copy()        # save coefficients
 
         return states, inputs
 
diff --git a/control/xferfcn.py b/control/xferfcn.py
index 02ba72df4..8e51534d7 100644
--- a/control/xferfcn.py
+++ b/control/xferfcn.py
@@ -1350,7 +1350,7 @@ def _c2d_matched(sysC, Ts, **kwargs):
         zpoles[idx] = z
         pregainden[idx] = 1 - z
     zgain = np.multiply.reduce(pregainnum) / np.multiply.reduce(pregainden)
-    gain = sysC.dcgain() / zgain
+    gain = sysC.dcgain() / zgain.real
     sysDnum, sysDden = zpk2tf(zzeros, zpoles, gain)
     return TransferFunction(sysDnum, sysDden, Ts, **kwargs)