diff --git a/pygsti/modelmembers/povms/basepovm.py b/pygsti/modelmembers/povms/basepovm.py
index 859d2e158..e953a9bad 100644
--- a/pygsti/modelmembers/povms/basepovm.py
+++ b/pygsti/modelmembers/povms/basepovm.py
@@ -75,7 +75,10 @@ def __init__(self, effects, evotype=None, state_space=None, preserve_sum=False,
         paramlbls = []
         for k, v in items:
             if k == self.complement_label: continue
-            if isinstance(v, _POVMEffect):
+            if called_from_reduce:  # __reduce__ should always initialize w/POVMEffects except for ...
+                assert isinstance(v, _POVMEffect)  # complement (which hits continue above)
+                effect = v  # don't copy as we want to preserve the gpindices in effects
+            elif isinstance(v, _POVMEffect):
                 effect = v if (not preserve_sum) else v.copy()  # .copy() just to de-allocate parameters
             else:
                 assert(evotype is not None), "Must specify `evotype` when effect vectors are not POVMEffect objects!"
@@ -108,7 +111,7 @@ def __init__(self, effects, evotype=None, state_space=None, preserve_sum=False,
             identity_for_complement = _np.array(sum([v.to_dense().reshape(comp_val.shape) for v in non_comp_effects])
                                                 + comp_val, 'd')  # ensure shapes match before summing
             complement_effect = _ComplementPOVMEffect(
-                identity_for_complement, non_comp_effects)
+                identity_for_complement, non_comp_effects, called_from_reduce)
             items.append((self.complement_label, complement_effect))
 
         super(_BasePOVM, self).__init__(state_space, evotype, None, items)
diff --git a/pygsti/modelmembers/povms/complementeffect.py b/pygsti/modelmembers/povms/complementeffect.py
index 4ca129222..16d328762 100644
--- a/pygsti/modelmembers/povms/complementeffect.py
+++ b/pygsti/modelmembers/povms/complementeffect.py
@@ -43,7 +43,7 @@ class ComplementPOVMEffect(_ConjugatedStatePOVMEffect):
         "complement" POVM effect vector.
     """
 
-    def __init__(self, identity, other_effects):
+    def __init__(self, identity, other_effects, called_from_reduce=False):
         evotype = other_effects[0]._evotype
         state_space = other_effects[0].state_space
 
@@ -62,8 +62,11 @@ def __init__(self, identity, other_effects):
         # 2) set the gpindices of the elements of other_spamvecs so
         #    that they index into our local parameter vector.
 
-        _ConjugatedStatePOVMEffect.__init__(self, self.identity.copy())
-        self.init_gpindices()  # initialize our gpindices based on sub-members
+        _ConjugatedStatePOVMEffect.__init__(self, self.identity.copy(), called_from_reduce)
+        if not called_from_reduce:
+            self.init_gpindices()  # initialize our gpindices based on sub-members
+        else:
+            self.allocate_gpindices(10000, None, submembers_already_allocated=True)
         self._construct_vector()  # reset's self.base
 
     def _construct_vector(self):
diff --git a/pygsti/modelmembers/povms/conjugatedeffect.py b/pygsti/modelmembers/povms/conjugatedeffect.py
index 9ffacb76d..a97178261 100644
--- a/pygsti/modelmembers/povms/conjugatedeffect.py
+++ b/pygsti/modelmembers/povms/conjugatedeffect.py
@@ -139,12 +139,15 @@ class ConjugatedStatePOVMEffect(DenseEffectInterface, _POVMEffect):
         i.e, a (dim,1)-shaped array.
     """
 
-    def __init__(self, state):
+    def __init__(self, state, called_from_reduce=False):
         self.state = state
         evotype = state._evotype
         rep = evotype.create_conjugatedstate_effect_rep(state._rep)
         _POVMEffect.__init__(self, rep, evotype)
-        self.init_gpindices()  # initialize our gpindices based on sub-members
+        if not called_from_reduce:
+            self.init_gpindices()  # initialize our gpindices based on sub-members
+        else:
+            self.allocate_gpindices(10000, None, submembers_already_allocated=True)
 
     @property
     def _basis(self):