diff --git a/python/adjoint/optimization_problem.py b/python/adjoint/optimization_problem.py
index c871cf6ba..a700d49bc 100644
--- a/python/adjoint/optimization_problem.py
+++ b/python/adjoint/optimization_problem.py
@@ -304,6 +304,12 @@ def calculate_gradient(self):
             for ar in range(len(self.objective_functions))
         ]
 
+        for dri in range(self.num_design_regions):
+            for i in range(3):
+                # note that dft_fields::remove calls delete on its chunks, and the
+                # destructor ~dft_chunk automatically removes it from the fields object
+                self.forward_design_region_monitors[dri][i].remove()
+
         # Cleanup list of lists
         if len(self.gradient) == 1:
             self.gradient = self.gradient[0]  # only one objective function
diff --git a/src/meepgeom.cpp b/src/meepgeom.cpp
index 15fa04076..b9a8feedc 100644
--- a/src/meepgeom.cpp
+++ b/src/meepgeom.cpp
@@ -2999,7 +2999,6 @@ void material_grids_addgradient(double *v, size_t ng, size_t nf,
   for (int i = 0; i < 3; i++) {
     for (int ii = 0; ii < adjoint_dft_chunks[i].size(); ii++) {
       delete adjoint_dft_chunks[i][ii];
-      delete forward_dft_chunks[i][ii];
     }
   }